diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5d4917a71..580e6e264 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -122,7 +122,7 @@ jobs:
       - run: opam install . --best-effort
         if: ${{ matrix.skip-test }}
 
-      - run: cat VERSION | xargs opam pin wasm_of_ocaml-compiler . -n --with-version 
+      - run: cat VERSION | xargs opam pin . -n --with-version 
         if: ${{ !matrix.skip-test }}
         shell: bash
 
@@ -164,44 +164,4 @@ jobs:
           branch: wikidoc
           folder: doc-dev
           clean: true
-          target-folder: doc/dev/
-
-  lint-opam:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout tree
-        uses: actions/checkout@v4
-      - name: Set-up OCaml
-        uses: ocaml/setup-ocaml@v3
-        with:
-          ocaml-compiler: "5.2"
-          dune-cache: true
-      - name: Pin dune
-        run: |
-          opam pin add -n dune.3.17 https://github.com/ocaml/dune.git
-      - uses: ocaml/setup-ocaml/lint-opam@v3
-
-  lint-fmt:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout tree
-        uses: actions/checkout@v4
-      - name: Set-up OCaml
-        uses: ocaml/setup-ocaml@v3
-        with:
-          ocaml-compiler: "5.2"
-          dune-cache: true
-      - name: Pin dune
-        run: |
-          opam pin add -n dune.3.17 https://github.com/ocaml/dune.git
-      - uses: ocaml/setup-ocaml/lint-fmt@v3
-
-  lint-runtime:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout tree
-        uses: actions/checkout@v4
-      - name: Set-up Biome
-        uses: biomejs/setup-biome@v2
-      - name: Run biome
-        run: biome ci
+          target-folder: doc/dev/
\ No newline at end of file
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 000000000..36f9a8c5e
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,48 @@
+name: lint
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  lint-opam:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout tree
+        uses: actions/checkout@v4
+      - name: Set-up OCaml
+        uses: ocaml/setup-ocaml@v3
+        with:
+          ocaml-compiler: "5.2"
+          dune-cache: true
+      - name: Pin dune
+        run: |
+          opam pin add -n dune.3.17 https://github.com/ocaml/dune.git
+      - uses: ocaml/setup-ocaml/lint-opam@v3
+
+  lint-fmt:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout tree
+        uses: actions/checkout@v4
+      - name: Set-up OCaml
+        uses: ocaml/setup-ocaml@v3
+        with:
+          ocaml-compiler: "5.2"
+          dune-cache: true
+      - name: Pin dune
+        run: |
+          opam pin add -n dune.3.17 https://github.com/ocaml/dune.git
+      - uses: ocaml/setup-ocaml/lint-fmt@v3
+
+  lint-runtime:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout tree
+        uses: actions/checkout@v4
+      - name: Set-up Biome
+        uses: biomejs/setup-biome@v2
+      - name: Run biome
+        run: biome ci
diff --git a/CHANGES.md b/CHANGES.md
index cb0a41545..e0d314ad2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,16 +1,15 @@
-# dev
+# 5.9.0 (2024-11-22) - Lille
 
 ## Features/Changes
 * Misc: update testsuite to OCaml 5.2
 * Misc: CI uses opam.2.2 and no longer use sunset repo
 * Misc: yojson is no longer optional
 * Misc: reduce the diff with the wasm_of_ocaml fork
+* Misc: finalize support for OCaml 5.3
 * Compiler: speedup global_flow/global_deadcode pass on large bytecode
 * Compiler: improved global dead code elimination (#2206)
 * Compiler: speedup json parsing, relying on Yojson.Raw (#1640)
 * Compiler: Decode sourcemap mappings only when necessary (#1664)
-* Compiler: make indirect call using sequence instead of using the call method
-  [f.call(null, args)] becomes [(0,f)(args)]
 * Compiler: mark [TextEncoder] as reserved
 * Compiler: add support for the Wasm backend in parts of the pipeline, in
   prevision for the merge of wasm_of_ocaml
@@ -21,12 +20,15 @@
 * Compiler: Emit index source_map to avoid changing mappings (#1714, #1715)
 * Compiler: improved source map generation (#1716)
 * Runtime: change Sys.os_type on windows (Cygwin -> Win32)
-* Runtime: backtraces are really expensive, they need to be be explicitly
+* Runtime: backtraces are really expensive, they need to be explicitly
   requested at compile time (--enable with-js-error) or at startup (OCAMLRUNPARAM=b=1)
 * Runtime: allow dynlink of precompiled js with separate compilation (#1676)
 * Runtime: reimplement the runtime of weak and ephemeron (#1707)
 * Lib: Modify Typed_array API for compatibility with WebAssembly
+* Lib: add details element and toggle event (#1728)
 * Toplevel: no longer set globals for toplevel initialization
+* Runtime: precompute constants used in `caml_lxm_next` (#1730)
+* Runtime: cleanup runtime
 
 ## Bug fixes
 * Runtime: fix parsing of unsigned integers (0u2147483648) (#1633, #1666)
diff --git a/VERSION b/VERSION
index 5e21ca5a8..b3d91f9cf 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-5.8.2
+5.9.0
diff --git a/biome.json b/biome.json
index 5de4567ff..9a0658559 100644
--- a/biome.json
+++ b/biome.json
@@ -2,7 +2,7 @@
   "$schema": "https://biomejs.dev/schemas/1.9.1/schema.json",
   "files": {
     "include": ["runtime"],
-    "ignore": ["runtime/zstd.ts"]
+    "ignore": ["runtime/js/zstd.ts"]
   },
   "formatter": {
     "enabled": true,
diff --git a/compiler/bin-js_of_ocaml/cmd_arg.ml b/compiler/bin-js_of_ocaml/cmd_arg.ml
index 58cf49053..c294be23a 100644
--- a/compiler/bin-js_of_ocaml/cmd_arg.ml
+++ b/compiler/bin-js_of_ocaml/cmd_arg.ml
@@ -130,7 +130,7 @@ let options =
   in
   let no_sourcemap =
     let doc =
-      "Don't generate source map. All other source map related flags will be be ignored."
+      "Don't generate source map. All other source map related flags will be ignored."
     in
     Arg.(value & flag & info [ "no-sourcemap"; "no-source-map" ] ~doc)
   in
@@ -395,7 +395,7 @@ let options_runtime_only =
   in
   let no_sourcemap =
     let doc =
-      "Don't generate source map. All other source map related flags will be be ignored."
+      "Don't generate source map. All other source map related flags will be ignored."
     in
     Arg.(value & flag & info [ "no-sourcemap"; "no-source-map" ] ~doc)
   in
diff --git a/compiler/bin-js_of_ocaml/link.ml b/compiler/bin-js_of_ocaml/link.ml
index 521ab6f70..f48c333fe 100644
--- a/compiler/bin-js_of_ocaml/link.ml
+++ b/compiler/bin-js_of_ocaml/link.ml
@@ -39,7 +39,7 @@ let options =
   in
   let no_sourcemap =
     let doc =
-      "Don't generate source map. All other source map related flags will be be ignored."
+      "Don't generate source map. All other source map related flags will be ignored."
     in
     Arg.(value & flag & info [ "no-sourcemap"; "no-source-map" ] ~doc)
   in
diff --git a/compiler/lib-runtime-files/dune b/compiler/lib-runtime-files/dune
index e9e77ae73..5742162d2 100644
--- a/compiler/lib-runtime-files/dune
+++ b/compiler/lib-runtime-files/dune
@@ -7,7 +7,7 @@
  (target files.ml)
  (deps
   gen/gen.exe
-  (glob_files ../../runtime/*.js))
+  (glob_files ../../runtime/js/*.js))
  (action
   (with-stdout-to
    %{target}
diff --git a/compiler/lib/flow_lexer.ml b/compiler/lib/flow_lexer.ml
index 526b71096..a3449fa32 100644
--- a/compiler/lib/flow_lexer.ml
+++ b/compiler/lib/flow_lexer.ml
@@ -832,9 +832,9 @@ let backquote env lexbuf =
 
 let wrap f =
   let f env =
-    let start, _ = Sedlexing.lexing_positions env.Lex_env.lex_lb in
+    let start = Sedlexing.lexing_position_start env.Lex_env.lex_lb in
     let t = f env env.Lex_env.lex_lb in
-    let _, stop = Sedlexing.lexing_positions env.Lex_env.lex_lb in
+    let stop = Sedlexing.lexing_position_curr env.Lex_env.lex_lb in
     t, Loc.create ~last_line:(Loc.line_end' !(env.lex_last_loc)) start stop
   in
   let rec helper comments env =
diff --git a/compiler/lib/generate.ml b/compiler/lib/generate.ml
index dbf057750..7784206d6 100644
--- a/compiler/lib/generate.ml
+++ b/compiler/lib/generate.ml
@@ -898,7 +898,8 @@ let apply_fun_raw ctx f params exact trampolined loc =
     (* Make sure we are performing a regular call, not a (slower)
        method call *)
     match f with
-    | J.EAccess _ | J.EDot _ -> J.call (J.ESeq (int 0, f)) params loc
+    | J.EAccess _ | J.EDot _ ->
+        J.call (J.dot f (Utf8_string.of_string_exn "call")) (s_var "null" :: params) loc
     | _ -> J.call f params loc
   in
   let apply =
diff --git a/compiler/lib/parse_bytecode.ml b/compiler/lib/parse_bytecode.ml
index b3fbc6c1b..667f62c5c 100644
--- a/compiler/lib/parse_bytecode.ml
+++ b/compiler/lib/parse_bytecode.ml
@@ -88,8 +88,6 @@ module Debug : sig
 
   val create : include_cmis:bool -> bool -> t
 
-  val fold : t -> (Code.Addr.t -> Instruct.debug_event -> 'a -> 'a) -> 'a -> 'a
-
   val paths : t -> units:StringSet.t -> StringSet.t
 end = struct
   open Instruct
@@ -315,9 +313,6 @@ end = struct
     | [], [] -> ()
     | _ -> assert false
 
-  let fold t f acc =
-    Int_table.fold (fun k { event; _ } acc -> f k event acc) t.events_by_pc acc
-
   let paths t ~units =
     let paths =
       Hashtbl.fold
@@ -333,46 +328,38 @@ end
 module Blocks : sig
   type t
 
-  val analyse : Debug.t -> bytecode -> t
-
-  val add : t -> int -> t
-
-  type u
-
-  val finish_analysis : t -> u
+  val analyse : bytecode -> t
 
-  val next : u -> int -> int
+  val next : t -> int -> int
 
-  val is_empty : u -> bool
+  val is_empty : t -> bool
 end = struct
-  type t = Addr.Set.t
-
-  type u = int array
+  type t = int array
 
   let add blocks pc = Addr.Set.add pc blocks
 
-  let rec scan debug blocks code pc len =
+  let rec scan blocks code pc len =
     if pc < len
     then
       match (get_instr_exn code pc).kind with
-      | KNullary -> scan debug blocks code (pc + 1) len
-      | KUnary -> scan debug blocks code (pc + 2) len
-      | KBinary -> scan debug blocks code (pc + 3) len
-      | KNullaryCall -> scan debug blocks code (pc + 1) len
-      | KUnaryCall -> scan debug blocks code (pc + 2) len
-      | KBinaryCall -> scan debug blocks code (pc + 3) len
+      | KNullary -> scan blocks code (pc + 1) len
+      | KUnary -> scan blocks code (pc + 2) len
+      | KBinary -> scan blocks code (pc + 3) len
+      | KNullaryCall -> scan blocks code (pc + 1) len
+      | KUnaryCall -> scan blocks code (pc + 2) len
+      | KBinaryCall -> scan blocks code (pc + 3) len
       | KJump ->
           let offset = gets code (pc + 1) in
           let blocks = Addr.Set.add (pc + offset + 1) blocks in
-          scan debug blocks code (pc + 2) len
+          scan blocks code (pc + 2) len
       | KCond_jump ->
           let offset = gets code (pc + 1) in
           let blocks = Addr.Set.add (pc + offset + 1) blocks in
-          scan debug blocks code (pc + 2) len
+          scan blocks code (pc + 2) len
       | KCmp_jump ->
           let offset = gets code (pc + 2) in
           let blocks = Addr.Set.add (pc + offset + 2) blocks in
-          scan debug blocks code (pc + 3) len
+          scan blocks code (pc + 3) len
       | KSwitch ->
           let sz = getu code (pc + 1) in
           let blocks = ref blocks in
@@ -380,19 +367,17 @@ end = struct
             let offset = gets code (pc + 2 + i) in
             blocks := Addr.Set.add (pc + offset + 2) !blocks
           done;
-          scan debug !blocks code (pc + 2 + (sz land 0xffff) + (sz lsr 16)) len
+          scan !blocks code (pc + 2 + (sz land 0xffff) + (sz lsr 16)) len
       | KClosurerec ->
           let nfuncs = getu code (pc + 1) in
-          scan debug blocks code (pc + nfuncs + 3) len
-      | KClosure -> scan debug blocks code (pc + 3) len
-      | KStop n -> scan debug blocks code (pc + n + 1) len
+          scan blocks code (pc + nfuncs + 3) len
+      | KClosure -> scan blocks code (pc + 3) len
+      | KStop n -> scan blocks code (pc + n + 1) len
       | K_will_not_happen -> assert false
     else (
       assert (pc = len);
       blocks)
 
-  let finish_analysis blocks = Array.of_list (Addr.Set.elements blocks)
-
   (* invariant: a.(i) <= x < a.(j) *)
   let rec find a i j x =
     assert (i < j);
@@ -406,17 +391,13 @@ end = struct
 
   let is_empty x = Array.length x <= 1
 
-  let analyse debug_data code =
-    let debug_data =
-      if Debug.enabled debug_data
-      then debug_data
-      else Debug.create ~include_cmis:false false
-    in
+  let analyse code =
     let blocks = Addr.Set.empty in
     let len = String.length code / 4 in
     let blocks = add blocks 0 in
     let blocks = add blocks len in
-    scan debug_data blocks code 0 len
+    let blocks = scan blocks code 0 len in
+    Array.of_list (Addr.Set.elements blocks)
 end
 
 (* Parse constants *)
@@ -806,7 +787,7 @@ let method_cache_id = ref 1
 let clo_offset_3 = if new_closure_repr then 3 else 2
 
 type compile_info =
-  { blocks : Blocks.u
+  { blocks : Blocks.t
   ; code : string
   ; limit : int
   ; debug : Debug.t
@@ -1865,7 +1846,7 @@ and compile infos pc state (instrs : instr list) =
 
         if debug_parser ()
         then (
-          Format.printf "%a = ccal \"%s\" (" Var.print x prim;
+          Format.printf "%a = ccall \"%s\" (" Var.print x prim;
           for i = 0 to nargs - 1 do
             if i > 0 then Format.printf ", ";
             Format.printf "%a" Var.print (List.nth args i)
@@ -1885,7 +1866,7 @@ and compile infos pc state (instrs : instr list) =
 
         if debug_parser ()
         then (
-          Format.printf "%a = ccal \"%s\" (" Var.print x prim;
+          Format.printf "%a = ccall \"%s\" (" Var.print x prim;
           for i = 0 to nargs - 1 do
             if i > 0 then Format.printf ", ";
             Format.printf "%a" Var.print (List.nth args i)
@@ -1905,7 +1886,7 @@ and compile infos pc state (instrs : instr list) =
 
         if debug_parser ()
         then (
-          Format.printf "%a = ccal \"%s\" (" Var.print x prim;
+          Format.printf "%a = ccall \"%s\" (" Var.print x prim;
           for i = 0 to nargs - 1 do
             if i > 0 then Format.printf ", ";
             Format.printf "%a" Var.print (List.nth args i)
@@ -2465,14 +2446,7 @@ type one =
 let parse_bytecode code globals debug_data =
   let state = State.initial globals in
   Code.Var.reset ();
-  let blocks = Blocks.analyse debug_data code in
-  let blocks =
-    (* Disabled. [pc] might not be an appropriate place to split blocks *)
-    if false && Debug.enabled debug_data
-    then Debug.fold debug_data (fun pc _ blocks -> Blocks.add blocks pc) blocks
-    else blocks
-  in
-  let blocks' = Blocks.finish_analysis blocks in
+  let blocks' = Blocks.analyse code in
   let p =
     if not (Blocks.is_empty blocks')
     then (
diff --git a/compiler/lib/parse_js.ml b/compiler/lib/parse_js.ml
index e8a4e5353..13c9c4aca 100644
--- a/compiler/lib/parse_js.ml
+++ b/compiler/lib/parse_js.ml
@@ -85,7 +85,7 @@ end = struct
     Option.iter filename ~f:(Sedlexing.set_filename l);
     create ?report_error l
 
-  let curr_pos lexbuf = snd (Sedlexing.lexing_positions lexbuf.l)
+  let curr_pos lexbuf = Sedlexing.lexing_position_curr lexbuf.l
 
   let report_errors t res =
     match Flow_lexer.Lex_result.errors res with
diff --git a/compiler/tests-check-prim/dune b/compiler/tests-check-prim/dune
index 88cf01f81..4b786374d 100644
--- a/compiler/tests-check-prim/dune
+++ b/compiler/tests-check-prim/dune
@@ -1,6 +1,6 @@
 (executables
  (names main)
- (libraries js_of_ocaml num)
+ (libraries js_of_ocaml num str)
  (link_flags
   (:standard -linkall))
  (modules main)
@@ -8,7 +8,7 @@
 
 (executables
  (names unix)
- (libraries js_of_ocaml num unix)
+ (libraries js_of_ocaml num str unix)
  (link_flags
   (:standard -linkall))
  (modules unix)
@@ -23,7 +23,8 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:js_of_ocaml} check-runtime +toplevel.js %{dep:main.bc}))))
+   (run %{bin:js_of_ocaml} check-runtime +dynlink.js +toplevel.js
+    %{dep:main.bc}))))
 
 (rule
  (targets unix-unix.output)
@@ -36,7 +37,8 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:js_of_ocaml} check-runtime +toplevel.js %{dep:unix.bc}))))
+   (run %{bin:js_of_ocaml} check-runtime +dynlink.js +toplevel.js
+    %{dep:unix.bc}))))
 
 (rule
  (targets unix-win32.output)
@@ -49,7 +51,8 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:js_of_ocaml} check-runtime +toplevel.js %{dep:unix.bc}))))
+   (run %{bin:js_of_ocaml} check-runtime +dynlink.js +toplevel.js
+    %{dep:unix.bc}))))
 
 (rule
  (targets main.output5)
@@ -60,7 +63,8 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:js_of_ocaml} check-runtime +toplevel.js %{dep:main.bc}))))
+   (run %{bin:js_of_ocaml} check-runtime +dynlink.js +toplevel.js
+    %{dep:main.bc}))))
 
 (rule
  (targets unix-unix.output5)
@@ -73,7 +77,8 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:js_of_ocaml} check-runtime +toplevel.js %{dep:unix.bc}))))
+   (run %{bin:js_of_ocaml} check-runtime +dynlink.js +toplevel.js
+    %{dep:unix.bc}))))
 
 (rule
  (targets unix-win32.output5)
@@ -86,4 +91,5 @@
  (action
   (with-stdout-to
    %{targets}
-   (run %{bin:js_of_ocaml} check-runtime +toplevel.js %{dep:unix.bc}))))
+   (run %{bin:js_of_ocaml} check-runtime +dynlink.js +toplevel.js
+    %{dep:unix.bc}))))
diff --git a/compiler/tests-check-prim/main.output b/compiler/tests-check-prim/main.output
index b5d4c4d6b..3051f6b6e 100644
--- a/compiler/tests-check-prim/main.output
+++ b/compiler/tests-check-prim/main.output
@@ -3,11 +3,6 @@ Missing
 
 From main.bc:
 caml_alloc_dummy_function
-caml_dynlink_add_primitive
-caml_dynlink_close_lib
-caml_dynlink_get_current_libs
-caml_dynlink_lookup_symbol
-caml_dynlink_open_lib
 caml_int64_add_native
 caml_int64_and_native
 caml_int64_div_native
@@ -19,9 +14,7 @@ caml_int64_sub_native
 caml_int64_xor_native
 caml_int_as_pointer
 caml_reset_afl_instrumentation
-caml_signbit
 debugger
-is_digit_normalized
 
 Unused
 -------
@@ -41,32 +34,7 @@ caml_bigstring_blit_string_to_ba
 caml_bigstring_memcmp
 caml_hash_mix_bigstring
 
-From +domain.js:
-caml_atomic_cas
-caml_atomic_exchange
-caml_atomic_fetch_add
-caml_atomic_load
-caml_atomic_make_contended
-caml_domain_dls
-caml_domain_dls_get
-caml_domain_dls_set
-caml_domain_id
-caml_domain_spawn
-caml_ml_domain_cpu_relax
-caml_ml_domain_id
-caml_ml_domain_set_name
-caml_ml_domain_unique_token
-caml_recommended_domain_count
-
 From +effect.js:
-caml_alloc_stack
-caml_continuation_use_and_update_handler_noexc
-caml_continuation_use_noexc
-caml_get_continuation_callstack
-caml_ml_condition_broadcast
-caml_ml_condition_new
-caml_ml_condition_signal
-caml_ml_condition_wait
 jsoo_effect_not_supported
 
 From +fs.js:
@@ -76,10 +44,6 @@ caml_fs_init
 jsoo_create_file
 jsoo_create_file_extern
 
-From +gc.js:
-caml_memprof_discard
-caml_memprof_set
-
 From +graphics.js:
 caml_gr_arc_aux
 caml_gr_blit_image
@@ -129,18 +93,10 @@ caml_gr_text_size
 caml_gr_wait_event
 caml_gr_window_id
 
-From +hash.js:
-caml_string_hash
-
 From +ints.js:
 caml_div
 caml_mod
 
-From +io.js:
-caml_input_value_to_outside_heap
-caml_ml_input_bigarray
-caml_ml_output_bigarray
-
 From +jslib.js:
 caml_is_js
 caml_trampoline
@@ -149,49 +105,15 @@ caml_wrap_exception
 
 From +marshal.js:
 BigStringReader
-caml_input_value_from_string
 caml_marshal_constants
 
 From +mlBytes.js:
 caml_array_of_bytes
 caml_array_of_string
 caml_bytes_of_utf16_jsstring
-caml_new_string
 caml_string_concat
-caml_string_set16
-caml_string_set32
-caml_string_set64
-caml_string_unsafe_set
 caml_to_js_string
 
-From +nat.js:
-compare_nat_real
-
-From +obj.js:
-caml_lazy_read_result
-caml_lazy_reset_to_lazy
-caml_lazy_update_to_forcing
-caml_lazy_update_to_forward
-caml_obj_compare_and_swap
-caml_obj_is_block
-caml_obj_is_shared
-caml_obj_update_tag
-
-From +prng.js:
-caml_lxm_next
-
-From +runtime_events.js:
-caml_custom_event_index
-caml_ml_runtime_events_pause
-caml_ml_runtime_events_resume
-caml_ml_runtime_events_start
-caml_runtime_events_create_cursor
-caml_runtime_events_free_cursor
-caml_runtime_events_read_poll
-caml_runtime_events_user_register
-caml_runtime_events_user_resolve
-caml_runtime_events_user_write
-
 From +stdlib.js:
 caml_build_symbols
 caml_is_printable
@@ -199,15 +121,6 @@ caml_maybe_print_stats
 caml_register_global
 jsoo_toplevel_reloc
 
-From +str.js:
-caml_str_initialize
-re_match
-re_partial_match
-re_replacement_text
-re_search_backward
-re_search_forward
-re_string_match
-
 From +sync.js:
 MlMutex
 caml_ml_mutex_lock
@@ -219,20 +132,10 @@ From +sys.js:
 caml_fatal_uncaught_exception
 caml_format_exception
 caml_is_special_exception
-caml_register_channel_for_spacetime
 caml_set_static_env
-caml_spacetime_enabled
-caml_spacetime_only_works_for_native_code
-caml_sys_is_regular_file
 
 From +toplevel.js:
 caml_dynlink_get_bytecode_sections
-caml_static_alloc
-caml_static_free
-caml_terminfo_backup
-caml_terminfo_resume
-caml_terminfo_setup
-caml_terminfo_standout
 jsoo_toplevel_init_compile
 jsoo_toplevel_init_reloc
 
diff --git a/compiler/tests-check-prim/main.output5 b/compiler/tests-check-prim/main.output5
index 470dc712b..f685d9f19 100644
--- a/compiler/tests-check-prim/main.output5
+++ b/compiler/tests-check-prim/main.output5
@@ -5,16 +5,9 @@ From main.bc:
 caml_alloc_dummy_function
 caml_continuation_use
 caml_drop_continuation
-caml_dynlink_add_primitive
-caml_dynlink_close_lib
-caml_dynlink_get_current_libs
-caml_dynlink_lookup_symbol
-caml_dynlink_open_lib
 caml_int_as_pointer
 caml_reset_afl_instrumentation
-caml_signbit
 debugger
-is_digit_normalized
 
 Unused
 -------
@@ -34,9 +27,6 @@ caml_bigstring_blit_string_to_ba
 caml_bigstring_memcmp
 caml_hash_mix_bigstring
 
-From +domain.js:
-caml_ml_domain_set_name
-
 From +effect.js:
 jsoo_effect_not_supported
 
@@ -47,14 +37,6 @@ caml_fs_init
 jsoo_create_file
 jsoo_create_file_extern
 
-From +gc.js:
-caml_eventlog_pause
-caml_eventlog_resume
-caml_gc_huge_fallback_count
-caml_get_major_bucket
-caml_get_major_credit
-caml_memprof_set
-
 From +graphics.js:
 caml_gr_arc_aux
 caml_gr_blit_image
@@ -116,7 +98,6 @@ caml_wrap_exception
 
 From +marshal.js:
 BigStringReader
-caml_input_value_from_string
 caml_marshal_constants
 
 From +mlBytes.js:
@@ -124,21 +105,8 @@ caml_array_of_bytes
 caml_array_of_string
 caml_bytes_of_utf16_jsstring
 caml_string_concat
-caml_string_set16
-caml_string_set32
-caml_string_set64
-caml_string_unsafe_set
 caml_to_js_string
 
-From +nat.js:
-compare_nat_real
-
-From +obj.js:
-caml_obj_is_block
-caml_obj_make_forward
-caml_obj_set_tag
-caml_obj_truncate
-
 From +runtime_events.js:
 caml_runtime_events_create_cursor
 caml_runtime_events_free_cursor
@@ -152,33 +120,15 @@ caml_maybe_print_stats
 caml_register_global
 jsoo_toplevel_reloc
 
-From +str.js:
-caml_str_initialize
-re_match
-re_partial_match
-re_replacement_text
-re_search_backward
-re_search_forward
-re_string_match
-
 From +sys.js:
 caml_fatal_uncaught_exception
 caml_format_exception
 caml_is_special_exception
-caml_register_channel_for_spacetime
 caml_set_static_env
-caml_spacetime_enabled
-caml_spacetime_only_works_for_native_code
 caml_sys_const_naked_pointers_checked
 
 From +toplevel.js:
 caml_get_section_table
-caml_static_alloc
-caml_static_free
-caml_terminfo_backup
-caml_terminfo_resume
-caml_terminfo_setup
-caml_terminfo_standout
 jsoo_toplevel_init_compile
 jsoo_toplevel_init_reloc
 
diff --git a/compiler/tests-check-prim/unix-unix.output b/compiler/tests-check-prim/unix-unix.output
index 3d6399954..a5b4b7b99 100644
--- a/compiler/tests-check-prim/unix-unix.output
+++ b/compiler/tests-check-prim/unix-unix.output
@@ -3,11 +3,6 @@ Missing
 
 From unix.bc:
 caml_alloc_dummy_function
-caml_dynlink_add_primitive
-caml_dynlink_close_lib
-caml_dynlink_get_current_libs
-caml_dynlink_lookup_symbol
-caml_dynlink_open_lib
 caml_int64_add_native
 caml_int64_and_native
 caml_int64_div_native
@@ -19,10 +14,8 @@ caml_int64_sub_native
 caml_int64_xor_native
 caml_int_as_pointer
 caml_reset_afl_instrumentation
-caml_signbit
 caml_unix_map_file_bytecode
 debugger
-is_digit_normalized
 unix_accept
 unix_access
 unix_alarm
@@ -150,32 +143,7 @@ caml_bigstring_blit_string_to_ba
 caml_bigstring_memcmp
 caml_hash_mix_bigstring
 
-From +domain.js:
-caml_atomic_cas
-caml_atomic_exchange
-caml_atomic_fetch_add
-caml_atomic_load
-caml_atomic_make_contended
-caml_domain_dls
-caml_domain_dls_get
-caml_domain_dls_set
-caml_domain_id
-caml_domain_spawn
-caml_ml_domain_cpu_relax
-caml_ml_domain_id
-caml_ml_domain_set_name
-caml_ml_domain_unique_token
-caml_recommended_domain_count
-
 From +effect.js:
-caml_alloc_stack
-caml_continuation_use_and_update_handler_noexc
-caml_continuation_use_noexc
-caml_get_continuation_callstack
-caml_ml_condition_broadcast
-caml_ml_condition_new
-caml_ml_condition_signal
-caml_ml_condition_wait
 jsoo_effect_not_supported
 
 From +fs.js:
@@ -185,10 +153,6 @@ caml_fs_init
 jsoo_create_file
 jsoo_create_file_extern
 
-From +gc.js:
-caml_memprof_discard
-caml_memprof_set
-
 From +graphics.js:
 caml_gr_arc_aux
 caml_gr_blit_image
@@ -238,18 +202,10 @@ caml_gr_text_size
 caml_gr_wait_event
 caml_gr_window_id
 
-From +hash.js:
-caml_string_hash
-
 From +ints.js:
 caml_div
 caml_mod
 
-From +io.js:
-caml_input_value_to_outside_heap
-caml_ml_input_bigarray
-caml_ml_output_bigarray
-
 From +jslib.js:
 caml_is_js
 caml_trampoline
@@ -258,49 +214,15 @@ caml_wrap_exception
 
 From +marshal.js:
 BigStringReader
-caml_input_value_from_string
 caml_marshal_constants
 
 From +mlBytes.js:
 caml_array_of_bytes
 caml_array_of_string
 caml_bytes_of_utf16_jsstring
-caml_new_string
 caml_string_concat
-caml_string_set16
-caml_string_set32
-caml_string_set64
-caml_string_unsafe_set
 caml_to_js_string
 
-From +nat.js:
-compare_nat_real
-
-From +obj.js:
-caml_lazy_read_result
-caml_lazy_reset_to_lazy
-caml_lazy_update_to_forcing
-caml_lazy_update_to_forward
-caml_obj_compare_and_swap
-caml_obj_is_block
-caml_obj_is_shared
-caml_obj_update_tag
-
-From +prng.js:
-caml_lxm_next
-
-From +runtime_events.js:
-caml_custom_event_index
-caml_ml_runtime_events_pause
-caml_ml_runtime_events_resume
-caml_ml_runtime_events_start
-caml_runtime_events_create_cursor
-caml_runtime_events_free_cursor
-caml_runtime_events_read_poll
-caml_runtime_events_user_register
-caml_runtime_events_user_resolve
-caml_runtime_events_user_write
-
 From +stdlib.js:
 caml_build_symbols
 caml_is_printable
@@ -308,15 +230,6 @@ caml_maybe_print_stats
 caml_register_global
 jsoo_toplevel_reloc
 
-From +str.js:
-caml_str_initialize
-re_match
-re_partial_match
-re_replacement_text
-re_search_backward
-re_search_forward
-re_string_match
-
 From +sync.js:
 MlMutex
 caml_ml_mutex_lock
@@ -328,20 +241,10 @@ From +sys.js:
 caml_fatal_uncaught_exception
 caml_format_exception
 caml_is_special_exception
-caml_register_channel_for_spacetime
 caml_set_static_env
-caml_spacetime_enabled
-caml_spacetime_only_works_for_native_code
-caml_sys_is_regular_file
 
 From +toplevel.js:
 caml_dynlink_get_bytecode_sections
-caml_static_alloc
-caml_static_free
-caml_terminfo_backup
-caml_terminfo_resume
-caml_terminfo_setup
-caml_terminfo_standout
 jsoo_toplevel_init_compile
 jsoo_toplevel_init_reloc
 
diff --git a/compiler/tests-check-prim/unix-unix.output5 b/compiler/tests-check-prim/unix-unix.output5
index 3ac8083bb..7902a823d 100644
--- a/compiler/tests-check-prim/unix-unix.output5
+++ b/compiler/tests-check-prim/unix-unix.output5
@@ -5,14 +5,8 @@ From unix.bc:
 caml_alloc_dummy_function
 caml_continuation_use
 caml_drop_continuation
-caml_dynlink_add_primitive
-caml_dynlink_close_lib
-caml_dynlink_get_current_libs
-caml_dynlink_lookup_symbol
-caml_dynlink_open_lib
 caml_int_as_pointer
 caml_reset_afl_instrumentation
-caml_signbit
 caml_unix_accept
 caml_unix_access
 caml_unix_alarm
@@ -125,7 +119,6 @@ caml_unix_waitpid
 caml_unix_write
 caml_unix_write_bigarray
 debugger
-is_digit_normalized
 
 Unused
 -------
@@ -145,9 +138,6 @@ caml_bigstring_blit_string_to_ba
 caml_bigstring_memcmp
 caml_hash_mix_bigstring
 
-From +domain.js:
-caml_ml_domain_set_name
-
 From +effect.js:
 jsoo_effect_not_supported
 
@@ -158,14 +148,6 @@ caml_fs_init
 jsoo_create_file
 jsoo_create_file_extern
 
-From +gc.js:
-caml_eventlog_pause
-caml_eventlog_resume
-caml_gc_huge_fallback_count
-caml_get_major_bucket
-caml_get_major_credit
-caml_memprof_set
-
 From +graphics.js:
 caml_gr_arc_aux
 caml_gr_blit_image
@@ -227,7 +209,6 @@ caml_wrap_exception
 
 From +marshal.js:
 BigStringReader
-caml_input_value_from_string
 caml_marshal_constants
 
 From +mlBytes.js:
@@ -235,21 +216,8 @@ caml_array_of_bytes
 caml_array_of_string
 caml_bytes_of_utf16_jsstring
 caml_string_concat
-caml_string_set16
-caml_string_set32
-caml_string_set64
-caml_string_unsafe_set
 caml_to_js_string
 
-From +nat.js:
-compare_nat_real
-
-From +obj.js:
-caml_obj_is_block
-caml_obj_make_forward
-caml_obj_set_tag
-caml_obj_truncate
-
 From +runtime_events.js:
 caml_runtime_events_create_cursor
 caml_runtime_events_free_cursor
@@ -263,33 +231,15 @@ caml_maybe_print_stats
 caml_register_global
 jsoo_toplevel_reloc
 
-From +str.js:
-caml_str_initialize
-re_match
-re_partial_match
-re_replacement_text
-re_search_backward
-re_search_forward
-re_string_match
-
 From +sys.js:
 caml_fatal_uncaught_exception
 caml_format_exception
 caml_is_special_exception
-caml_register_channel_for_spacetime
 caml_set_static_env
-caml_spacetime_enabled
-caml_spacetime_only_works_for_native_code
 caml_sys_const_naked_pointers_checked
 
 From +toplevel.js:
 caml_get_section_table
-caml_static_alloc
-caml_static_free
-caml_terminfo_backup
-caml_terminfo_resume
-caml_terminfo_setup
-caml_terminfo_standout
 jsoo_toplevel_init_compile
 jsoo_toplevel_init_reloc
 
diff --git a/compiler/tests-check-prim/unix-win32.output b/compiler/tests-check-prim/unix-win32.output
index 9df6df3c0..284f7eb51 100644
--- a/compiler/tests-check-prim/unix-win32.output
+++ b/compiler/tests-check-prim/unix-win32.output
@@ -3,11 +3,6 @@ Missing
 
 From unix.bc:
 caml_alloc_dummy_function
-caml_dynlink_add_primitive
-caml_dynlink_close_lib
-caml_dynlink_get_current_libs
-caml_dynlink_lookup_symbol
-caml_dynlink_open_lib
 caml_int64_add_native
 caml_int64_and_native
 caml_int64_div_native
@@ -19,10 +14,8 @@ caml_int64_sub_native
 caml_int64_xor_native
 caml_int_as_pointer
 caml_reset_afl_instrumentation
-caml_signbit
 caml_unix_map_file_bytecode
 debugger
-is_digit_normalized
 unix_accept
 unix_access
 unix_bind
@@ -115,32 +108,7 @@ caml_bigstring_blit_string_to_ba
 caml_bigstring_memcmp
 caml_hash_mix_bigstring
 
-From +domain.js:
-caml_atomic_cas
-caml_atomic_exchange
-caml_atomic_fetch_add
-caml_atomic_load
-caml_atomic_make_contended
-caml_domain_dls
-caml_domain_dls_get
-caml_domain_dls_set
-caml_domain_id
-caml_domain_spawn
-caml_ml_domain_cpu_relax
-caml_ml_domain_id
-caml_ml_domain_set_name
-caml_ml_domain_unique_token
-caml_recommended_domain_count
-
 From +effect.js:
-caml_alloc_stack
-caml_continuation_use_and_update_handler_noexc
-caml_continuation_use_noexc
-caml_get_continuation_callstack
-caml_ml_condition_broadcast
-caml_ml_condition_new
-caml_ml_condition_signal
-caml_ml_condition_wait
 jsoo_effect_not_supported
 
 From +fs.js:
@@ -150,10 +118,6 @@ caml_fs_init
 jsoo_create_file
 jsoo_create_file_extern
 
-From +gc.js:
-caml_memprof_discard
-caml_memprof_set
-
 From +graphics.js:
 caml_gr_arc_aux
 caml_gr_blit_image
@@ -203,18 +167,10 @@ caml_gr_text_size
 caml_gr_wait_event
 caml_gr_window_id
 
-From +hash.js:
-caml_string_hash
-
 From +ints.js:
 caml_div
 caml_mod
 
-From +io.js:
-caml_input_value_to_outside_heap
-caml_ml_input_bigarray
-caml_ml_output_bigarray
-
 From +jslib.js:
 caml_is_js
 caml_trampoline
@@ -223,49 +179,15 @@ caml_wrap_exception
 
 From +marshal.js:
 BigStringReader
-caml_input_value_from_string
 caml_marshal_constants
 
 From +mlBytes.js:
 caml_array_of_bytes
 caml_array_of_string
 caml_bytes_of_utf16_jsstring
-caml_new_string
 caml_string_concat
-caml_string_set16
-caml_string_set32
-caml_string_set64
-caml_string_unsafe_set
 caml_to_js_string
 
-From +nat.js:
-compare_nat_real
-
-From +obj.js:
-caml_lazy_read_result
-caml_lazy_reset_to_lazy
-caml_lazy_update_to_forcing
-caml_lazy_update_to_forward
-caml_obj_compare_and_swap
-caml_obj_is_block
-caml_obj_is_shared
-caml_obj_update_tag
-
-From +prng.js:
-caml_lxm_next
-
-From +runtime_events.js:
-caml_custom_event_index
-caml_ml_runtime_events_pause
-caml_ml_runtime_events_resume
-caml_ml_runtime_events_start
-caml_runtime_events_create_cursor
-caml_runtime_events_free_cursor
-caml_runtime_events_read_poll
-caml_runtime_events_user_register
-caml_runtime_events_user_resolve
-caml_runtime_events_user_write
-
 From +stdlib.js:
 caml_build_symbols
 caml_is_printable
@@ -273,15 +195,6 @@ caml_maybe_print_stats
 caml_register_global
 jsoo_toplevel_reloc
 
-From +str.js:
-caml_str_initialize
-re_match
-re_partial_match
-re_replacement_text
-re_search_backward
-re_search_forward
-re_string_match
-
 From +sync.js:
 MlMutex
 caml_ml_mutex_lock
@@ -293,20 +206,10 @@ From +sys.js:
 caml_fatal_uncaught_exception
 caml_format_exception
 caml_is_special_exception
-caml_register_channel_for_spacetime
 caml_set_static_env
-caml_spacetime_enabled
-caml_spacetime_only_works_for_native_code
-caml_sys_is_regular_file
 
 From +toplevel.js:
 caml_dynlink_get_bytecode_sections
-caml_static_alloc
-caml_static_free
-caml_terminfo_backup
-caml_terminfo_resume
-caml_terminfo_setup
-caml_terminfo_standout
 jsoo_toplevel_init_compile
 jsoo_toplevel_init_reloc
 
diff --git a/compiler/tests-check-prim/unix-win32.output5 b/compiler/tests-check-prim/unix-win32.output5
index 7db584011..b45443271 100644
--- a/compiler/tests-check-prim/unix-win32.output5
+++ b/compiler/tests-check-prim/unix-win32.output5
@@ -5,14 +5,8 @@ From unix.bc:
 caml_alloc_dummy_function
 caml_continuation_use
 caml_drop_continuation
-caml_dynlink_add_primitive
-caml_dynlink_close_lib
-caml_dynlink_get_current_libs
-caml_dynlink_lookup_symbol
-caml_dynlink_open_lib
 caml_int_as_pointer
 caml_reset_afl_instrumentation
-caml_signbit
 caml_unix_accept
 caml_unix_access
 caml_unix_bind
@@ -91,7 +85,6 @@ caml_unix_waitpid
 caml_unix_write
 caml_unix_write_bigarray
 debugger
-is_digit_normalized
 
 Unused
 -------
@@ -111,9 +104,6 @@ caml_bigstring_blit_string_to_ba
 caml_bigstring_memcmp
 caml_hash_mix_bigstring
 
-From +domain.js:
-caml_ml_domain_set_name
-
 From +effect.js:
 jsoo_effect_not_supported
 
@@ -124,14 +114,6 @@ caml_fs_init
 jsoo_create_file
 jsoo_create_file_extern
 
-From +gc.js:
-caml_eventlog_pause
-caml_eventlog_resume
-caml_gc_huge_fallback_count
-caml_get_major_bucket
-caml_get_major_credit
-caml_memprof_set
-
 From +graphics.js:
 caml_gr_arc_aux
 caml_gr_blit_image
@@ -193,7 +175,6 @@ caml_wrap_exception
 
 From +marshal.js:
 BigStringReader
-caml_input_value_from_string
 caml_marshal_constants
 
 From +mlBytes.js:
@@ -201,21 +182,8 @@ caml_array_of_bytes
 caml_array_of_string
 caml_bytes_of_utf16_jsstring
 caml_string_concat
-caml_string_set16
-caml_string_set32
-caml_string_set64
-caml_string_unsafe_set
 caml_to_js_string
 
-From +nat.js:
-compare_nat_real
-
-From +obj.js:
-caml_obj_is_block
-caml_obj_make_forward
-caml_obj_set_tag
-caml_obj_truncate
-
 From +runtime_events.js:
 caml_runtime_events_create_cursor
 caml_runtime_events_free_cursor
@@ -229,33 +197,15 @@ caml_maybe_print_stats
 caml_register_global
 jsoo_toplevel_reloc
 
-From +str.js:
-caml_str_initialize
-re_match
-re_partial_match
-re_replacement_text
-re_search_backward
-re_search_forward
-re_string_match
-
 From +sys.js:
 caml_fatal_uncaught_exception
 caml_format_exception
 caml_is_special_exception
-caml_register_channel_for_spacetime
 caml_set_static_env
-caml_spacetime_enabled
-caml_spacetime_only_works_for_native_code
 caml_sys_const_naked_pointers_checked
 
 From +toplevel.js:
 caml_get_section_table
-caml_static_alloc
-caml_static_free
-caml_terminfo_backup
-caml_terminfo_resume
-caml_terminfo_setup
-caml_terminfo_standout
 jsoo_toplevel_init_compile
 jsoo_toplevel_init_reloc
 
diff --git a/compiler/tests-compiler/direct_calls.ml b/compiler/tests-compiler/direct_calls.ml
index eac493b74..e458e8391 100644
--- a/compiler/tests-compiler/direct_calls.ml
+++ b/compiler/tests-compiler/direct_calls.ml
@@ -84,8 +84,8 @@ let%expect_test "direct calls without --enable effects" =
     //end
     function test3(x){
      function F(symbol){function f(x){return x + 1 | 0;} return [0, f];}
-     var M1 = F([0]), M2 = F([0]), _b_ = (0, M2[1])(2);
-     return [0, (0, M1[1])(1), _b_];
+     var M1 = F([0]), M2 = F([0]), _b_ = M2[1].call(null, 2);
+     return [0, M1[1].call(null, 1), _b_];
     }
     //end
     function test4(x){
@@ -94,11 +94,10 @@ let%expect_test "direct calls without --enable effects" =
       return [0, f];
      }
      var M1 = F([0]), M2 = F([0]);
-     (0, M1[1])(1);
-     return (0, M2[1])(2);
+     M1[1].call(null, 1);
+     return M2[1].call(null, 2);
     }
-    //end
-    |}]
+    //end |}]
 
 let%expect_test "direct calls with --enable effects" =
   let code =
@@ -179,8 +178,8 @@ let%expect_test "direct calls with --enable effects" =
     //end
     function test3(x, cont){
      function F(symbol){function f(x){return x + 1 | 0;} return [0, f];}
-     var M1 = F(), M2 = F(), _c_ = (0, M2[1])(2);
-     return cont([0, (0, M1[1])(1), _c_]);
+     var M1 = F(), M2 = F(), _c_ = M2[1].call(null, 2);
+     return cont([0, M1[1].call(null, 1), _c_]);
     }
     //end
     function test4(x, cont){
diff --git a/compiler/tests-compiler/dune.inc b/compiler/tests-compiler/dune.inc
index 4524092ab..4a4f76bf4 100644
--- a/compiler/tests-compiler/dune.inc
+++ b/compiler/tests-compiler/dune.inc
@@ -659,6 +659,36 @@
  (preprocess
   (pps ppx_expect)))
 
+(library
+ ;; compiler/tests-compiler/rec.ml
+ (name rec_15)
+ (enabled_if %{env:js-enabled=})
+ (modules rec)
+ (libraries js_of_ocaml_compiler unix str jsoo_compiler_expect_tests_helper)
+ (inline_tests
+  (enabled_if (< %{ocaml_version} 5.2))
+  (deps
+   (file %{project_root}/compiler/bin-js_of_ocaml/js_of_ocaml.exe)
+   (file %{project_root}/compiler/bin-jsoo_minify/jsoo_minify.exe)))
+ (flags (:standard -open Jsoo_compiler_expect_tests_helper))
+ (preprocess
+  (pps ppx_expect)))
+
+(library
+ ;; compiler/tests-compiler/rec52.ml
+ (name rec52_15)
+ (enabled_if %{env:js-enabled=})
+ (modules rec52)
+ (libraries js_of_ocaml_compiler unix str jsoo_compiler_expect_tests_helper)
+ (inline_tests
+  (enabled_if (>= %{ocaml_version} 5.2))
+  (deps
+   (file %{project_root}/compiler/bin-js_of_ocaml/js_of_ocaml.exe)
+   (file %{project_root}/compiler/bin-jsoo_minify/jsoo_minify.exe)))
+ (flags (:standard -open Jsoo_compiler_expect_tests_helper))
+ (preprocess
+  (pps ppx_expect)))
+
 (library
  ;; compiler/tests-compiler/scopes.ml
  (name scopes_15)
diff --git a/compiler/tests-compiler/gen-rules/gen.ml b/compiler/tests-compiler/gen-rules/gen.ml
index ef0415518..bee62eb18 100644
--- a/compiler/tests-compiler/gen-rules/gen.ml
+++ b/compiler/tests-compiler/gen-rules/gen.ml
@@ -47,6 +47,8 @@ let prefix : string =
 
 type enabled_if =
   | GE5
+  | GE52
+  | LT52
   | B64
   | Any
 
@@ -58,12 +60,15 @@ let lib_enabled_if = function
 let test_enabled_if = function
   | "obj" | "lazy" -> GE5
   | "gh1051" -> B64
+  | "rec52" -> GE52
+  | "rec" -> LT52
   | _ -> Any
 
-let enabled_if cond =
-  match cond with
+let enabled_if = function
   | Any -> "true"
   | GE5 -> "(>= %{ocaml_version} 5)"
+  | GE52 -> "(>= %{ocaml_version} 5.2)"
+  | LT52 -> "(< %{ocaml_version} 5.2)"
   | B64 -> "%{arch_sixtyfour}"
 
 let js_enabled = function
diff --git a/compiler/tests-compiler/rec.ml b/compiler/tests-compiler/rec.ml
new file mode 100644
index 000000000..a5085f4ef
--- /dev/null
+++ b/compiler/tests-compiler/rec.ml
@@ -0,0 +1,83 @@
+(* Js_of_ocaml compiler
+ * http://www.ocsigen.org/js_of_ocaml/
+ * Copyright (C) 2024 Hugo Heuzard
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, with linking exception;
+ * either version 2.1 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *)
+
+open Util
+
+let%expect_test "let rec" =
+  let p =
+    {|
+      let rec a x =
+        (* syntactic function *)
+        b x
+      and b =
+        (* non-syntactic function *)
+        let tbl : (int, int) Hashtbl.t = Hashtbl.create 17 in
+        fun x -> `T (tbl, c, a 0)
+      and c =
+        (* block *)
+        Some (d, default)
+      and d =
+        (* 'dynamic' value (not recursive *)
+        Array.make 5 0
+      and default =
+        (* constant, with (spurious) use
+           of a recursive neighbor *)
+        let _ = a in
+        42
+   |}
+  in
+  let p = compile_and_parse p in
+  print_program p;
+  [%expect
+    {|
+    (function(globalThis){
+       "use strict";
+       var
+        runtime = globalThis.jsoo_runtime,
+        caml_update_dummy = runtime.caml_update_dummy;
+       function caml_call1(f, a0){
+        return (f.l >= 0 ? f.l : f.l = f.length) === 1
+                ? f(a0)
+                : runtime.caml_call_gen(f, [a0]);
+       }
+       function caml_call2(f, a0, a1){
+        return (f.l >= 0 ? f.l : f.l = f.length) === 2
+                ? f(a0, a1)
+                : runtime.caml_call_gen(f, [a0, a1]);
+       }
+       var
+        global_data = runtime.caml_get_global_data(),
+        Stdlib_Hashtbl = global_data.Stdlib__Hashtbl,
+        a = function _d_(_c_){return _d_.fun(_c_);},
+        b = function _b_(_a_){return _b_.fun(_a_);},
+        c = [],
+        d = runtime.caml_make_vect(5, 0),
+        default$0 = 42;
+       caml_update_dummy(a, function(x){return caml_call1(b, x);});
+       var tbl = caml_call2(Stdlib_Hashtbl[1], 0, 17);
+       caml_update_dummy
+        (b, function(x){return [0, 84, [0, tbl, c, caml_call1(a, 0)]];});
+       caml_update_dummy(c, [0, [0, d, default$0]]);
+       var Test = [0, a, b, c, d, default$0];
+       runtime.caml_register_global(1, Test, "Test");
+       return;
+      }
+      (globalThis));
+    //end
+    |}]
diff --git a/compiler/tests-compiler/rec52.ml b/compiler/tests-compiler/rec52.ml
new file mode 100644
index 000000000..18d766eea
--- /dev/null
+++ b/compiler/tests-compiler/rec52.ml
@@ -0,0 +1,80 @@
+(* Js_of_ocaml compiler
+ * http://www.ocsigen.org/js_of_ocaml/
+ * Copyright (C) 2024 Hugo Heuzard
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, with linking exception;
+ * either version 2.1 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *)
+
+open Util
+
+let%expect_test "let rec" =
+  let p =
+    {|
+      let rec a x =
+        (* syntactic function *)
+        b x
+      and b =
+        (* non-syntactic function *)
+        let tbl : (int, int) Hashtbl.t = Hashtbl.create 17 in
+        fun x -> `T (tbl, c, a 0)
+      and c =
+        (* block *)
+        Some (d, default)
+      and d =
+        (* 'dynamic' value (not recursive *)
+        Array.make 5 0
+      and default =
+        (* constant, with (spurious) use
+           of a recursive neighbor *)
+        let _ = a in
+        42
+   |}
+  in
+  let p = compile_and_parse p in
+  print_program p;
+  [%expect
+    {|
+    (function(globalThis){
+       "use strict";
+       var
+        runtime = globalThis.jsoo_runtime,
+        caml_update_dummy = runtime.caml_update_dummy;
+       function caml_call2(f, a0, a1){
+        return (f.l >= 0 ? f.l : f.l = f.length) === 2
+                ? f(a0, a1)
+                : runtime.caml_call_gen(f, [a0, a1]);
+       }
+       var
+        global_data = runtime.caml_get_global_data(),
+        Stdlib_Hashtbl = global_data.Stdlib__Hashtbl,
+        letrec_function_context = [],
+        c = [],
+        d = runtime.caml_make_vect(5, 0),
+        default$0 = 42;
+       function a(x){return b(x);}
+       function b(x){
+        var _a_ = b(0);
+        return [0, 84, [0, letrec_function_context[1], c, _a_]];
+       }
+       var tbl = caml_call2(Stdlib_Hashtbl[1], 0, 17);
+       caml_update_dummy(letrec_function_context, [0, tbl]);
+       caml_update_dummy(c, [0, [0, d, default$0]]);
+       var Test = [0, a, b, c, d, default$0];
+       runtime.caml_register_global(1, Test, "Test");
+       return;
+      }
+      (globalThis));
+    //end
+    |}]
diff --git a/dune-project b/dune-project
index 9a564c6bb..6be93f23c 100644
--- a/dune-project
+++ b/dune-project
@@ -24,12 +24,12 @@
   (ppxlib (>= 0.15.0))
   (re :with-test)
   (cmdliner (>= 1.1.0))
-  (sedlex (>= 2.3))
+  (sedlex (>= 3.3))
   (qcheck :with-test)
   menhir
   menhirLib
   menhirSdk
-  yojson)
+  (yojson (>= 1.6)))
  (depopts
   ocamlfind)
  (conflicts
diff --git a/js_of_ocaml-compiler.opam b/js_of_ocaml-compiler.opam
index 273a95508..8eb65727b 100644
--- a/js_of_ocaml-compiler.opam
+++ b/js_of_ocaml-compiler.opam
@@ -19,12 +19,12 @@ depends: [
   "ppxlib" {>= "0.15.0"}
   "re" {with-test}
   "cmdliner" {>= "1.1.0"}
-  "sedlex" {>= "2.3"}
+  "sedlex" {>= "3.3"}
   "qcheck" {with-test}
   "menhir"
   "menhirLib"
   "menhirSdk"
-  "yojson"
+  "yojson" {>= "1.6"}
   "odoc" {with-doc}
 ]
 depopts: ["ocamlfind"]
diff --git a/lib/js_of_ocaml/dom_html.ml b/lib/js_of_ocaml/dom_html.ml
index a58215b44..ed556ee03 100644
--- a/lib/js_of_ocaml/dom_html.ml
+++ b/lib/js_of_ocaml/dom_html.ml
@@ -452,6 +452,14 @@ and clipboardEvent = object
   method clipboardData : dataTransfer t readonly_prop
 end
 
+and toggleEvent = object
+  inherit event
+
+  method newState : js_string t readonly_prop
+
+  method oldState : js_string t readonly_prop
+end
+
 and dataTransfer = object
   method dropEffect : js_string t prop
 
@@ -959,6 +967,8 @@ module Event = struct
 
   let waiting = Dom.Event.make "waiting"
 
+  let toggle = Dom.Event.make "toggle"
+
   let make = Dom.Event.make
 end
 
@@ -1372,6 +1382,16 @@ class type anchorElement = object
   method _type : js_string t prop
 end
 
+class type detailsElement = object ('self)
+  inherit element
+
+  method open_ : bool t prop
+
+  method name : js_string t prop
+
+  method ontoggle : ('self t, toggleEvent t) event_listener prop
+end
+
 class type imageElement = object ('self)
   inherit element
 
@@ -2736,6 +2756,8 @@ module CoerceTo = struct
 
   let del e = unsafeCoerce "del" e
 
+  let details e = unsafeCoerce "details" e
+
   let div e = unsafeCoerce "div" e
 
   let dl e = unsafeCoerce "dl" e
diff --git a/lib/js_of_ocaml/dom_html.mli b/lib/js_of_ocaml/dom_html.mli
index 000778d8b..5e00793cd 100644
--- a/lib/js_of_ocaml/dom_html.mli
+++ b/lib/js_of_ocaml/dom_html.mli
@@ -458,6 +458,14 @@ and clipboardEvent = object
   method clipboardData : dataTransfer t readonly_prop
 end
 
+and toggleEvent = object
+  inherit event
+
+  method newState : js_string t readonly_prop
+
+  method oldState : js_string t readonly_prop
+end
+
 and dataTransfer = object
   method dropEffect : js_string t prop
 
@@ -1190,6 +1198,16 @@ class type anchorElement = object
   method _type : js_string t prop
 end
 
+class type detailsElement = object ('self)
+  inherit element
+
+  method open_ : bool t prop
+
+  method name : js_string t prop
+
+  method ontoggle : ('self t, toggleEvent t) event_listener prop
+end
+
 class type imageElement = object ('self)
   inherit element
 
@@ -2503,6 +2521,8 @@ module Event : sig
 
   val waiting : mediaEvent t typ
 
+  val toggle : toggleEvent t typ
+
   val make : string -> 'a typ
 end
 
@@ -3048,6 +3068,8 @@ module CoerceTo : sig
 
   val del : #element t -> modElement t opt
 
+  val details : #element t -> detailsElement t opt
+
   val div : #element t -> divElement t opt
 
   val embed : #element t -> embedElement t opt
diff --git a/lib/js_of_ocaml/js.ml b/lib/js_of_ocaml/js.ml
index d432e8319..8a5ccdece 100644
--- a/lib/js_of_ocaml/js.ml
+++ b/lib/js_of_ocaml/js.ml
@@ -812,17 +812,16 @@ let parseFloat (s : js_string t) : number_t =
   let s = Unsafe.fun_call Unsafe.global##.parseFloat [| Unsafe.inject s |] in
   if isNaN s then failwith "parseFloat" else s
 
-let _ =
-  Printexc.register_printer (function
-      | Js_error.Exn e -> Some (Js_error.to_string e)
-      | _ -> None)
-
 let _ =
   Printexc.register_printer (fun e ->
-      let e : < .. > t = Obj.magic e in
-      if instanceof e error_constr
-      then Some (Js_error.to_string (Js_error.of_error e))
-      else None)
+      if instanceof (Obj.magic e : < .. > t) error_constr
+      then
+        let e = Js_error.of_error (Obj.magic e : error t) in
+        Some (Js_error.to_string e)
+      else
+        match e with
+        | Js_error.Exn e -> Some (Js_error.to_string e)
+        | _ -> None)
 
 let export_js (field : js_string t) x =
   Unsafe.set
diff --git a/lib/js_of_ocaml/sys_js.mli b/lib/js_of_ocaml/sys_js.mli
index 0c06137ac..02f146e52 100644
--- a/lib/js_of_ocaml/sys_js.mli
+++ b/lib/js_of_ocaml/sys_js.mli
@@ -54,7 +54,7 @@ val read_file : name:string -> string
 val create_file : name:string -> content:string -> unit
 (** Register a file to a Pseudo Filesystem.
       [create_file ~name ~content] register the file [name] with content [content]
-      so it can be be opened with [open_in name] *)
+      so it can be opened with [open_in name] *)
 
 val update_file : name:string -> content:string -> unit
 (** Update a file in the Pseudo Filesystem.
diff --git a/lib/tyxml/tyxml_cast.ml b/lib/tyxml/tyxml_cast.ml
index 53c21ffec..9e3cad874 100644
--- a/lib/tyxml/tyxml_cast.ml
+++ b/lib/tyxml/tyxml_cast.ml
@@ -79,6 +79,8 @@ end) : Tyxml_cast_sigs.TO with type 'a elt = 'a C.elt = struct
 
   let of_li elt = rebuild_node "of_li" elt
 
+  let of_details elt = rebuild_node "of_details" elt
+
   let of_dialog elt = rebuild_node "of_dialog" elt
 
   let of_div elt = rebuild_node "of_div" elt
@@ -177,8 +179,6 @@ end) : Tyxml_cast_sigs.TO with type 'a elt = 'a C.elt = struct
 
   let of_dd elt = rebuild_node "of_dd" elt
 
-  let of_details elt = rebuild_node "of_details" elt
-
   let of_dfn elt = rebuild_node "of_dfn" elt
 
   let of_dt elt = rebuild_node "of_dt" elt
@@ -311,6 +311,8 @@ end) : Tyxml_cast_sigs.OF with type 'a elt = 'a C.elt = struct
 
   let of_li elt = rebuild_node "of_li" elt
 
+  let of_details elt = rebuild_node "of_details" elt
+
   let of_dialog elt = rebuild_node "of_dialog" elt
 
   let of_div elt = rebuild_node "of_div" elt
diff --git a/lib/tyxml/tyxml_cast_sigs.ml b/lib/tyxml/tyxml_cast_sigs.ml
index 08d8605ce..a6ea2b76c 100644
--- a/lib/tyxml/tyxml_cast_sigs.ml
+++ b/lib/tyxml/tyxml_cast_sigs.ml
@@ -71,6 +71,8 @@ module type OF = sig
 
   val of_li : Dom_html.liElement Js.t -> [> Html_types.li ] elt
 
+  val of_details : Dom_html.detailsElement Js.t -> [> Html_types.details ] elt
+
   val of_dialog : Dom_html.dialogElement Js.t -> [> Html_types.dialog ] elt
 
   val of_div : Dom_html.divElement Js.t -> [> Html_types.div ] elt
@@ -182,6 +184,8 @@ module type TO = sig
 
   val of_li : [< Html_types.li ] elt -> Dom_html.liElement Js.t
 
+  val of_details : [< Html_types.details ] elt -> Dom_html.detailsElement Js.t
+
   val of_dialog : [< Html_types.dialog ] elt -> Dom_html.dialogElement Js.t
 
   val of_div : [< Html_types.div ] elt -> Dom_html.divElement Js.t
@@ -280,8 +284,6 @@ module type TO = sig
 
   val of_dd : [> Html_types.dd ] elt -> Dom_html.element Js.t
 
-  val of_details : [> Html_types.details ] elt -> Dom_html.element Js.t
-
   val of_dfn : [> Html_types.dfn ] elt -> Dom_html.element Js.t
 
   val of_dt : [> Html_types.dt ] elt -> Dom_html.element Js.t
diff --git a/lib/tyxml/tyxml_cast_sigs.mli b/lib/tyxml/tyxml_cast_sigs.mli
index 42007a2ec..a09731674 100644
--- a/lib/tyxml/tyxml_cast_sigs.mli
+++ b/lib/tyxml/tyxml_cast_sigs.mli
@@ -70,6 +70,8 @@ module type OF = sig
 
   val of_li : Dom_html.liElement Js.t -> [> Html_types.li ] elt
 
+  val of_details : Dom_html.detailsElement Js.t -> [> Html_types.details ] elt
+
   val of_dialog : Dom_html.dialogElement Js.t -> [> Html_types.dialog ] elt
 
   val of_div : Dom_html.divElement Js.t -> [> Html_types.div ] elt
@@ -181,6 +183,8 @@ module type TO = sig
 
   val of_li : [< Html_types.li ] elt -> Dom_html.liElement Js.t
 
+  val of_details : [< Html_types.details ] elt -> Dom_html.detailsElement Js.t
+
   val of_dialog : [< Html_types.dialog ] elt -> Dom_html.dialogElement Js.t
 
   val of_div : [< Html_types.div ] elt -> Dom_html.divElement Js.t
@@ -279,8 +283,6 @@ module type TO = sig
 
   val of_dd : [> Html_types.dd ] elt -> Dom_html.element Js.t
 
-  val of_details : [> Html_types.details ] elt -> Dom_html.element Js.t
-
   val of_dfn : [> Html_types.dfn ] elt -> Dom_html.element Js.t
 
   val of_dt : [> Html_types.dt ] elt -> Dom_html.element Js.t
diff --git a/runtime/array.js b/runtime/js/array.js
similarity index 78%
rename from runtime/array.js
rename to runtime/js/array.js
index e276c1e40..280abb551 100644
--- a/runtime/array.js
+++ b/runtime/js/array.js
@@ -34,6 +34,13 @@ function caml_floatarray_sub(a, i, len) {
   return caml_array_sub(a, i, len);
 }
 
+//Provides: caml_uniform_array_sub mutable
+//Requires: caml_array_sub
+//Version: >= 5.3
+function caml_uniform_array_sub(a, i, len) {
+  return caml_array_sub(a, i, len);
+}
+
 //Provides: caml_array_append mutable
 function caml_array_append(a1, a2) {
   var l1 = a1.length,
@@ -55,6 +62,13 @@ function caml_floatarray_append(a1, a2) {
   return caml_array_append(a1, a2);
 }
 
+//Provides: caml_uniform_array_append mutable
+//Requires: caml_array_append
+//Version: >= 5.3
+function caml_uniform_array_append(a1, a2) {
+  return caml_array_append(a1, a2);
+}
+
 //Provides: caml_array_concat mutable
 function caml_array_concat(l) {
   var a = [0];
@@ -82,6 +96,13 @@ function caml_floatarray_blit(a1, i1, a2, i2, len) {
   return caml_array_blit(a1, i1, a2, i2, len);
 }
 
+//Provides: caml_uniform_array_blit
+//Requires: caml_array_blit
+//Version: >= 5.3
+function caml_uniform_array_blit(a1, i1, a2, i2, len) {
+  return caml_array_blit(a1, i1, a2, i2, len);
+}
+
 ///////////// Pervasive
 //Provides: caml_array_set (mutable, const, mutable)
 //Requires: caml_array_bound_error
@@ -113,6 +134,20 @@ function caml_floatarray_fill(array, ofs, len, v) {
   return caml_array_fill(array, ofs, len, v);
 }
 
+//Provides: caml_floatarray_fill_unboxed
+//Requires: caml_array_fill
+//Version: >= 5.3
+function caml_floatarray_fill_unboxed(array, ofs, len, v) {
+  return caml_array_fill(array, ofs, len, v);
+}
+
+//Provides: caml_uniform_array_fill
+//Requires: caml_array_fill
+//Version: >= 5.3
+function caml_uniform_array_fill(array, ofs, len, v) {
+  return caml_array_fill(array, ofs, len, v);
+}
+
 //Provides: caml_check_bound (mutable, const)
 //Requires: caml_array_bound_error
 function caml_check_bound(array, index) {
@@ -176,3 +211,17 @@ function caml_floatarray_create(len) {
 function caml_floatarray_make(len, init) {
   return caml_array_make(len, init);
 }
+
+//Provides: caml_floatarray_make_unboxed const (const)
+//Requires: caml_array_make
+//Version: >= 5.3
+function caml_floatarray_make_unboxed(len, init) {
+  return caml_array_make(len, init);
+}
+
+//Provides: caml_uniform_array_make const (const)
+//Requires: caml_array_make
+//Version: >= 5.3
+function caml_uniform_array_make(len, init) {
+  return caml_array_make(len, init);
+}
diff --git a/runtime/backtrace.js b/runtime/js/backtrace.js
similarity index 100%
rename from runtime/backtrace.js
rename to runtime/js/backtrace.js
diff --git a/runtime/bigarray.js b/runtime/js/bigarray.js
similarity index 100%
rename from runtime/bigarray.js
rename to runtime/js/bigarray.js
diff --git a/runtime/bigstring.js b/runtime/js/bigstring.js
similarity index 100%
rename from runtime/bigstring.js
rename to runtime/js/bigstring.js
diff --git a/runtime/blake2.js b/runtime/js/blake2.js
similarity index 89%
rename from runtime/blake2.js
rename to runtime/js/blake2.js
index ca17a471b..e7661230c 100644
--- a/runtime/blake2.js
+++ b/runtime/js/blake2.js
@@ -326,7 +326,7 @@ function caml_blake2_final(ctx, hashlen) {
 //Provides: caml_blake2_update
 //Requires: blake2b
 //Requires: caml_uint8_array_of_string
-//Version: >= 5.2
+//Version: >= 5.2, < 5.3
 function caml_blake2_update(ctx, buf, ofs, len) {
   var input = caml_uint8_array_of_string(buf);
   input = input.subarray(ofs, ofs + len);
@@ -334,13 +334,48 @@ function caml_blake2_update(ctx, buf, ofs, len) {
   return 0;
 }
 
+//Provides: caml_blake2_update
+//Requires: blake2b
+//Requires: caml_uint8_array_of_bytes
+//Version: >= 5.3
+function caml_blake2_update(ctx, buf, ofs, len) {
+  var input = caml_uint8_array_of_bytes(buf);
+  input = input.subarray(ofs, ofs + len);
+  blake2b.Update(ctx, input);
+  return 0;
+}
+
 //Provides: caml_blake2_string
 //Requires: caml_blake2_create
 //Requires: caml_blake2_update
 //Requires: caml_blake2_final
-//Version: >= 5.2
+//Version: >= 5.2, < 5.3
 function caml_blake2_string(hashlen, key, buf, ofs, len) {
   var ctx = caml_blake2_create(hashlen, key);
   caml_blake2_update(ctx, buf, ofs, len);
   return caml_blake2_final(ctx, hashlen);
 }
+
+//Provides: caml_blake2_string
+//Requires: caml_blake2_create
+//Requires: caml_blake2_update
+//Requires: caml_blake2_final
+//Requires: caml_bytes_of_string
+//Version: >= 5.3
+function caml_blake2_string(hashlen, key, buf_str, ofs, len) {
+  var ctx = caml_blake2_create(hashlen, key);
+  var buf = caml_bytes_of_string(buf_str);
+  caml_blake2_update(ctx, buf, ofs, len);
+  return caml_blake2_final(ctx, hashlen);
+}
+
+//Provides: caml_blake2_bytes
+//Requires: caml_blake2_create
+//Requires: caml_blake2_update
+//Requires: caml_blake2_final
+//Version: >= 5.3
+function caml_blake2_bytes(hashlen, key, buf, ofs, len) {
+  var ctx = caml_blake2_create(hashlen, key);
+  caml_blake2_update(ctx, buf, ofs, len);
+  return caml_blake2_final(ctx, hashlen);
+}
diff --git a/runtime/compare.js b/runtime/js/compare.js
similarity index 99%
rename from runtime/compare.js
rename to runtime/js/compare.js
index 609e2e613..315d76f90 100644
--- a/runtime/compare.js
+++ b/runtime/js/compare.js
@@ -61,7 +61,7 @@ function caml_compare_val_number_custom(num, custom, swap, total) {
   if (comp) {
     var x = swap > 0 ? comp(custom, num, total) : comp(num, custom, total);
     if (total && Number.isNaN(x)) return swap; // total && nan
-    if (Number.isNan(+x)) return +x; // nan
+    if (Number.isNaN(+x)) return +x; // nan
     if ((x | 0) !== 0) return x | 0; // !nan
   }
   return swap;
diff --git a/runtime/domain.js b/runtime/js/domain.js
similarity index 91%
rename from runtime/domain.js
rename to runtime/js/domain.js
index d441b2d0d..e2808c306 100644
--- a/runtime/domain.js
+++ b/runtime/js/domain.js
@@ -1,8 +1,10 @@
 //Provides: caml_domain_dls
+//Version: >= 5
 var caml_domain_dls = [0];
 
 //Provides: caml_domain_dls_set
 //Requires: caml_domain_dls
+//Version: >= 5
 function caml_domain_dls_set(a) {
   caml_domain_dls = a;
 }
@@ -18,16 +20,19 @@ function caml_domain_dls_compare_and_set(old, n) {
 
 //Provides: caml_domain_dls_get
 //Requires: caml_domain_dls
+//Version: >= 5
 function caml_domain_dls_get(unit) {
   return caml_domain_dls;
 }
 
 //Provides: caml_atomic_load
+//Version: >= 5
 function caml_atomic_load(ref) {
   return ref[1];
 }
 
 //Provides: caml_atomic_cas
+//Version: >= 5
 function caml_atomic_cas(ref, o, n) {
   if (ref[1] === o) {
     ref[1] = n;
@@ -37,6 +42,7 @@ function caml_atomic_cas(ref, o, n) {
 }
 
 //Provides: caml_atomic_fetch_add
+//Version: >= 5
 function caml_atomic_fetch_add(ref, i) {
   var old = ref[1];
   ref[1] += i;
@@ -44,6 +50,7 @@ function caml_atomic_fetch_add(ref, i) {
 }
 
 //Provides: caml_atomic_exchange
+//Version: >= 5
 function caml_atomic_exchange(ref, v) {
   var r = ref[1];
   ref[1] = v;
@@ -51,23 +58,20 @@ function caml_atomic_exchange(ref, v) {
 }
 
 //Provides: caml_atomic_make_contended
+//Version: >= 5.2
 function caml_atomic_make_contended(a) {
   return [0, a];
 }
 
 //Provides: caml_ml_domain_unique_token
-//Version: < 5.2
+//Version: >= 5.0, < 5.2
 var caml_ml_domain_unique_token_ = [0];
 function caml_ml_domain_unique_token(unit) {
   return caml_ml_domain_unique_token_;
 }
 
-//Provides: caml_ml_domain_set_name
-function caml_ml_domain_set_name(_name) {
-  return 0;
-}
-
 //Provides: caml_recommended_domain_count
+//Version: >= 5
 function caml_recommended_domain_count(unit) {
   return 1;
 }
@@ -80,6 +84,7 @@ function caml_ml_domain_index(unit) {
 }
 
 //Provides: caml_domain_id
+//Version: >= 5
 var caml_domain_id = 0;
 
 //Provides: caml_domain_spawn
@@ -104,7 +109,7 @@ function caml_domain_spawn(f, term_sync) {
 //Requires: caml_ml_mutex_unlock
 //Requires: caml_domain_id
 //Requires: caml_callback
-//Version: < 5.2
+//Version: >= 5.0, < 5.2
 var caml_domain_latest_idx = 1;
 function caml_domain_spawn(f, mutex) {
   var id = caml_domain_latest_idx++;
@@ -118,11 +123,13 @@ function caml_domain_spawn(f, mutex) {
 
 //Provides: caml_ml_domain_id
 //Requires: caml_domain_id
+//Version: >= 5.0
 function caml_ml_domain_id(unit) {
   return caml_domain_id;
 }
 
 //Provides: caml_ml_domain_cpu_relax
+//Version: >= 5
 function caml_ml_domain_cpu_relax(unit) {
   return 0;
 }
diff --git a/runtime/dune b/runtime/js/dune
similarity index 100%
rename from runtime/dune
rename to runtime/js/dune
diff --git a/runtime/dynlink.js b/runtime/js/dynlink.js
similarity index 98%
rename from runtime/dynlink.js
rename to runtime/js/dynlink.js
index 064827861..5f0f1dba4 100644
--- a/runtime/dynlink.js
+++ b/runtime/js/dynlink.js
@@ -73,16 +73,19 @@ function caml_dynlink_get_current_libs() {
 }
 
 //Provides: caml_register_code_fragment
+//Version: < 4.10
 function caml_register_code_fragment(code, codesize, digest) {
   return 0;
 }
 
 //Provides: caml_add_debug_info
+//Version: < 4.13
 function caml_add_debug_info(code, size, events) {
   return 0;
 }
 
 //Provides: caml_remove_debug_info
+//Version: < 4.13
 function caml_remove_debug_info(code) {
   return 0;
 }
diff --git a/runtime/effect.js b/runtime/js/effect.js
similarity index 97%
rename from runtime/effect.js
rename to runtime/js/effect.js
index d80a44493..3856e76bf 100644
--- a/runtime/effect.js
+++ b/runtime/js/effect.js
@@ -130,6 +130,7 @@ function caml_perform_effect(eff, cont, k0) {
 //Provides: caml_alloc_stack
 //Requires: caml_pop_fiber, caml_fiber_stack, caml_call_gen, caml_stack_check_depth, caml_trampoline_return
 //If: effects
+//Version: >= 5.0
 function caml_alloc_stack(hv, hx, hf) {
   function call(i, x) {
     var f = caml_fiber_stack.h[i];
@@ -151,11 +152,13 @@ function caml_alloc_stack(hv, hx, hf) {
 
 //Provides: caml_alloc_stack
 //If: !effects
+//Version: >= 5.0
 function caml_alloc_stack(hv, hx, hf) {
   return 0;
 }
 
 //Provides: caml_continuation_use_noexc
+//Version: >= 5.0
 function caml_continuation_use_noexc(cont) {
   var stack = cont[1];
   cont[1] = 0;
@@ -164,6 +167,7 @@ function caml_continuation_use_noexc(cont) {
 
 //Provides: caml_continuation_use_and_update_handler_noexc
 //Requires: caml_continuation_use_noexc
+//Version: >= 5.0
 function caml_continuation_use_and_update_handler_noexc(
   cont,
   hval,
@@ -176,26 +180,31 @@ function caml_continuation_use_and_update_handler_noexc(
 }
 
 //Provides: caml_get_continuation_callstack
+//Version: >= 5.0
 function caml_get_continuation_callstack() {
   return [0];
 }
 
 //Provides: caml_ml_condition_new
+//Version: >= 5.0
 function caml_ml_condition_new(unit) {
   return { condition: 1 };
 }
 
 //Provides: caml_ml_condition_wait
+//Version: >= 5.0
 function caml_ml_condition_wait(t, mutext) {
   return 0;
 }
 
 //Provides: caml_ml_condition_broadcast
+//Version: >= 5.0
 function caml_ml_condition_broadcast(t) {
   return 0;
 }
 
 //Provides: caml_ml_condition_signal
+//Version: >= 5.0
 function caml_ml_condition_signal(t) {
   return 0;
 }
diff --git a/runtime/fail.js b/runtime/js/fail.js
similarity index 100%
rename from runtime/fail.js
rename to runtime/js/fail.js
diff --git a/runtime/format.js b/runtime/js/format.js
similarity index 100%
rename from runtime/format.js
rename to runtime/js/format.js
diff --git a/runtime/fs.js b/runtime/js/fs.js
similarity index 100%
rename from runtime/fs.js
rename to runtime/js/fs.js
diff --git a/runtime/fs_fake.js b/runtime/js/fs_fake.js
similarity index 100%
rename from runtime/fs_fake.js
rename to runtime/js/fs_fake.js
diff --git a/runtime/fs_node.js b/runtime/js/fs_node.js
similarity index 100%
rename from runtime/fs_node.js
rename to runtime/js/fs_node.js
diff --git a/runtime/gc.js b/runtime/js/gc.js
similarity index 95%
rename from runtime/gc.js
rename to runtime/js/gc.js
index b531156f5..3692f8997 100644
--- a/runtime/gc.js
+++ b/runtime/js/gc.js
@@ -52,6 +52,7 @@ function caml_gc_get() {
 }
 
 //Provides: caml_memprof_set
+//Version: = 4.10
 function caml_memprof_set(_control) {
   return 0;
 }
@@ -92,21 +93,25 @@ function caml_memprof_stop(unit) {
 }
 
 //Provides: caml_memprof_discard
+//Version: >= 5.2
 function caml_memprof_discard(t) {
   return 0;
 }
 
 //Provides: caml_eventlog_resume
+//Version: < 5.0
 function caml_eventlog_resume(unit) {
   return 0;
 }
 
 //Provides: caml_eventlog_pause
+//Version: < 5.0
 function caml_eventlog_pause(unit) {
   return 0;
 }
 
 //Provides: caml_gc_huge_fallback_count
+//Version: < 5.0
 function caml_gc_huge_fallback_count(unit) {
   return 0;
 }
@@ -127,11 +132,13 @@ function caml_get_minor_free(unit) {
 }
 
 //Provides: caml_get_major_bucket
+//Version: < 5.0
 function caml_get_major_bucket(n) {
   return 0;
 }
 
 //Provides: caml_get_major_credit
+//Version: < 5.0
 function caml_get_major_credit(n) {
   return 0;
 }
diff --git a/runtime/graphics.js b/runtime/js/graphics.js
similarity index 100%
rename from runtime/graphics.js
rename to runtime/js/graphics.js
diff --git a/runtime/hash.js b/runtime/js/hash.js
similarity index 99%
rename from runtime/hash.js
rename to runtime/js/hash.js
index d20ee1498..61f7b617a 100644
--- a/runtime/hash.js
+++ b/runtime/js/hash.js
@@ -275,6 +275,7 @@ function caml_hash(count, limit, seed, obj) {
 
 //Provides: caml_string_hash
 //Requires: caml_hash_mix_final, caml_hash_mix_string
+//Version: >= 5.0
 function caml_string_hash(h, v) {
   var h = caml_hash_mix_string(h, v);
   var h = caml_hash_mix_final(h);
diff --git a/runtime/ieee_754.js b/runtime/js/ieee_754.js
similarity index 99%
rename from runtime/ieee_754.js
rename to runtime/js/ieee_754.js
index aa657f8c5..96491ec15 100644
--- a/runtime/ieee_754.js
+++ b/runtime/js/ieee_754.js
@@ -281,6 +281,7 @@ function caml_copysign_float(x, y) {
 }
 
 //Provides: caml_signbit_float const
+//Alias: caml_signbit
 function caml_signbit_float(x) {
   if (x === 0) x = 1 / x;
   return x < 0 ? 1 : 0;
diff --git a/runtime/int64.js b/runtime/js/int64.js
similarity index 100%
rename from runtime/int64.js
rename to runtime/js/int64.js
diff --git a/runtime/internalMod.js b/runtime/js/internalMod.js
similarity index 100%
rename from runtime/internalMod.js
rename to runtime/js/internalMod.js
diff --git a/runtime/ints.js b/runtime/js/ints.js
similarity index 100%
rename from runtime/ints.js
rename to runtime/js/ints.js
diff --git a/runtime/io.js b/runtime/js/io.js
similarity index 99%
rename from runtime/io.js
rename to runtime/js/io.js
index 35182f876..3a56fbd1b 100644
--- a/runtime/io.js
+++ b/runtime/js/io.js
@@ -338,6 +338,7 @@ function caml_ml_input(chanid, b, i, l) {
 //Provides: caml_ml_input_bigarray
 //Requires: caml_ml_input_block
 //Requires: caml_ba_to_typed_array
+//Version: >= 5.2
 function caml_ml_input_bigarray(chanid, b, i, l) {
   var ba = caml_ba_to_typed_array(b);
   return caml_ml_input_block(chanid, ba, i, l);
@@ -405,6 +406,7 @@ function caml_input_value(chanid) {
 
 //Provides: caml_input_value_to_outside_heap
 //Requires: caml_input_value
+//Version: >= 5
 function caml_input_value_to_outside_heap(c) {
   return caml_input_value(c);
 }
@@ -584,6 +586,7 @@ function caml_ml_output_bytes(chanid, buffer, offset, len) {
 
 //Provides: caml_ml_output_bigarray
 //Requires: caml_ba_to_typed_array, caml_ml_output_ta
+//Version: >= 5.2
 function caml_ml_output_bigarray(chanid, buffer, offset, len) {
   var buffer = caml_ba_to_typed_array(buffer);
   return caml_ml_output_ta(chanid, buffer, offset, len);
diff --git a/runtime/jslib.js b/runtime/js/jslib.js
similarity index 100%
rename from runtime/jslib.js
rename to runtime/js/jslib.js
diff --git a/runtime/jslib_js_of_ocaml.js b/runtime/js/jslib_js_of_ocaml.js
similarity index 100%
rename from runtime/jslib_js_of_ocaml.js
rename to runtime/js/jslib_js_of_ocaml.js
diff --git a/runtime/lexing.js b/runtime/js/lexing.js
similarity index 100%
rename from runtime/lexing.js
rename to runtime/js/lexing.js
diff --git a/runtime/marshal.js b/runtime/js/marshal.js
similarity index 99%
rename from runtime/marshal.js
rename to runtime/js/marshal.js
index ddb93f6f9..7e4aec531 100644
--- a/runtime/marshal.js
+++ b/runtime/js/marshal.js
@@ -233,6 +233,7 @@ function caml_float_of_bytes(a) {
 
 //Provides: caml_input_value_from_string mutable
 //Requires: MlStringReader, caml_input_value_from_reader
+//Version: < 4.12
 function caml_input_value_from_string(s, ofs) {
   var reader = new MlStringReader(s, typeof ofs === "number" ? ofs : ofs[0]);
   return caml_input_value_from_reader(reader, ofs);
diff --git a/runtime/md5.js b/runtime/js/md5.js
similarity index 100%
rename from runtime/md5.js
rename to runtime/js/md5.js
diff --git a/runtime/mlBytes.js b/runtime/js/mlBytes.js
similarity index 95%
rename from runtime/mlBytes.js
rename to runtime/js/mlBytes.js
index fe7e7f9c3..a39ae3a10 100644
--- a/runtime/mlBytes.js
+++ b/runtime/js/mlBytes.js
@@ -353,20 +353,6 @@ function caml_bytes_set16(s, i, i16) {
   return 0;
 }
 
-//Provides: caml_string_set16
-//Requires: caml_failwith
-//If: js-string
-function caml_string_set16(s, i, i16) {
-  caml_failwith("caml_string_set16");
-}
-
-//Provides: caml_string_set16
-//Requires: caml_bytes_set16
-//If: !js-string
-function caml_string_set16(s, i, i16) {
-  return caml_bytes_set16(s, i, i16);
-}
-
 //Provides: caml_bytes_set32
 //Requires: caml_bytes_bound_error, caml_bytes_unsafe_set
 function caml_bytes_set32(s, i, i32) {
@@ -382,20 +368,6 @@ function caml_bytes_set32(s, i, i32) {
   return 0;
 }
 
-//Provides: caml_string_set32
-//Requires: caml_failwith
-//If: js-string
-function caml_string_set32(s, i, i32) {
-  caml_failwith("caml_string_set32");
-}
-
-//Provides: caml_string_set32
-//Requires: caml_bytes_set32
-//If: !js-string
-function caml_string_set32(s, i, i32) {
-  return caml_bytes_set32(s, i, i32);
-}
-
 //Provides: caml_bytes_set64
 //Requires: caml_bytes_bound_error, caml_bytes_unsafe_set
 //Requires: caml_int64_to_bytes
@@ -408,20 +380,6 @@ function caml_bytes_set64(s, i, i64) {
   return 0;
 }
 
-//Provides: caml_string_set64
-//Requires: caml_failwith
-//If: js-string
-function caml_string_set64(s, i, i64) {
-  caml_failwith("caml_string_set64");
-}
-
-//Provides: caml_string_set64
-//Requires: caml_bytes_set64
-//If: !js-string
-function caml_string_set64(s, i, i64) {
-  return caml_bytes_set64(s, i, i64);
-}
-
 //Provides: caml_bytes_set
 //Requires: caml_bytes_bound_error, caml_bytes_unsafe_set
 function caml_bytes_set(s, i, c) {
@@ -712,13 +670,6 @@ function caml_string_unsafe_get(s, i) {
   return s.charCodeAt(i);
 }
 
-//Provides: caml_string_unsafe_set
-//Requires: caml_failwith
-//If: js-string
-function caml_string_unsafe_set(s, i, c) {
-  caml_failwith("caml_string_unsafe_set");
-}
-
 //Provides: caml_ml_string_length const
 //If: js-string
 function caml_ml_string_length(s) {
@@ -932,12 +883,6 @@ function caml_js_to_byte_string(s) {
   return caml_string_of_jsbytes(s);
 }
 
-//Provides: caml_new_string
-//Requires: caml_string_of_jsbytes
-function caml_new_string(s) {
-  return caml_string_of_jsbytes(s);
-}
-
 //Provides: caml_js_from_string mutable (const)
 //Requires: caml_jsstring_of_string
 function caml_js_from_string(s) {
diff --git a/runtime/nat.js b/runtime/js/nat.js
similarity index 98%
rename from runtime/nat.js
rename to runtime/js/nat.js
index 0af2a0689..cbeb1db26 100644
--- a/runtime/nat.js
+++ b/runtime/js/nat.js
@@ -143,6 +143,11 @@ function is_digit_zero(nat, ofs) {
   return 0;
 }
 
+//Provides: is_digit_normalized
+function is_digit_normalized(nat, ofs) {
+  return 1;
+}
+
 //Provides: is_digit_odd
 function is_digit_odd(nat, ofs) {
   if (nat.data[ofs] & 1) return 1;
@@ -418,12 +423,6 @@ function compare_nat(nat1, ofs1, len1, nat2, ofs2, len2) {
   return 0;
 }
 
-//Provides: compare_nat_real
-//Requires: compare_nat
-function compare_nat_real(nat1, nat2) {
-  return compare_nat(nat1, 0, nat1.data.length, nat2, 0, nat2.data.length);
-}
-
 //Provides: land_digit_nat
 function land_digit_nat(nat1, ofs1, nat2, ofs2) {
   nat1.data[ofs1] &= nat2.data[ofs2];
diff --git a/runtime/obj.js b/runtime/js/obj.js
similarity index 96%
rename from runtime/obj.js
rename to runtime/js/obj.js
index 405d87560..1dd73d985 100644
--- a/runtime/obj.js
+++ b/runtime/js/obj.js
@@ -39,6 +39,7 @@ function caml_alloc_dummy_infix() {
 }
 
 //Provides: caml_obj_is_block const (const)
+//Version: < 4.12
 function caml_obj_is_block(x) {
   return +Array.isArray(x);
 }
@@ -55,6 +56,7 @@ function caml_obj_tag(x) {
 }
 
 //Provides: caml_obj_set_tag (mutable, const)
+//Version: < 5.0
 function caml_obj_set_tag(x, tag) {
   x[0] = tag;
   return 0;
@@ -86,6 +88,7 @@ function caml_obj_dup(x) {
 
 //Provides: caml_obj_truncate (mutable, const)
 //Requires: caml_invalid_argument
+//Version: < 5.0
 function caml_obj_truncate(x, s) {
   if (s <= 0 || s + 1 > x.length) caml_invalid_argument("Obj.truncate");
   if (x.length !== s + 1) x.length = s + 1;
@@ -93,6 +96,7 @@ function caml_obj_truncate(x, s) {
 }
 
 //Provides: caml_obj_make_forward
+//Version: < 5.0
 function caml_obj_make_forward(b, v) {
   b[0] = 250;
   b[1] = v;
@@ -100,6 +104,7 @@ function caml_obj_make_forward(b, v) {
 }
 
 //Provides: caml_obj_compare_and_swap
+//Version: >= 5.0
 function caml_obj_compare_and_swap(x, i, old, n) {
   if (x[i + 1] === old) {
     x[i + 1] = n;
@@ -109,6 +114,7 @@ function caml_obj_compare_and_swap(x, i, old, n) {
 }
 
 //Provides: caml_obj_is_shared
+//Version: >= 5.0
 function caml_obj_is_shared(x) {
   return 1;
 }
@@ -182,6 +188,7 @@ function caml_obj_add_offset(v, offset) {
 }
 
 //Provides: caml_obj_update_tag
+//Version: >= 5.0
 function caml_obj_update_tag(b, o, n) {
   if (b[0] === o) {
     b[0] = n;
@@ -192,6 +199,7 @@ function caml_obj_update_tag(b, o, n) {
 
 //Provides: caml_lazy_update_to_forcing
 //Requires: caml_obj_update_tag
+//Version: >= 5.0
 function caml_lazy_update_to_forcing(o) {
   if (
     Array.isArray(o) &&
@@ -206,6 +214,7 @@ function caml_lazy_update_to_forcing(o) {
 
 //Provides: caml_lazy_update_to_forward
 //Requires: caml_obj_update_tag
+//Version: >= 5.0
 function caml_lazy_update_to_forward(o) {
   caml_obj_update_tag(o, 244, 250);
   return 0; // unit
@@ -213,6 +222,7 @@ function caml_lazy_update_to_forward(o) {
 
 //Provides: caml_lazy_reset_to_lazy
 //Requires: caml_obj_update_tag
+//Version: >= 5.0
 function caml_lazy_reset_to_lazy(o) {
   caml_obj_update_tag(o, 244, 246);
   return 0;
@@ -220,6 +230,7 @@ function caml_lazy_reset_to_lazy(o) {
 
 //Provides: caml_lazy_read_result
 //Requires: caml_obj_tag
+//Version: >= 5.0
 function caml_lazy_read_result(o) {
   return caml_obj_tag(o) === 250 ? o[1] : o;
 }
diff --git a/runtime/parsing.js b/runtime/js/parsing.js
similarity index 100%
rename from runtime/parsing.js
rename to runtime/js/parsing.js
diff --git a/runtime/prng.js b/runtime/js/prng.js
similarity index 75%
rename from runtime/prng.js
rename to runtime/js/prng.js
index 9bce1eafb..b4aaad6fa 100644
--- a/runtime/prng.js
+++ b/runtime/js/prng.js
@@ -1,3 +1,19 @@
+//Provides: caml_lxm_M
+//Requires: caml_int64_of_string
+//Requires: caml_string_of_jsstring
+//Version: >= 5
+var caml_lxm_M = caml_int64_of_string(
+  caml_string_of_jsstring("0xd1342543de82ef95"),
+);
+
+//Provides: caml_lxm_daba
+//Requires: caml_int64_of_string
+//Requires: caml_string_of_jsstring
+//Version: >= 5
+var caml_lxm_daba = caml_int64_of_string(
+  caml_string_of_jsstring("0xdaba0b6eb09322e3"),
+);
+
 //Provides: caml_lxm_next
 //Requires: caml_int64_shift_left
 //Requires: caml_int64_shift_right_unsigned
@@ -7,8 +23,9 @@
 //Requires: caml_int64_mul
 //Requires: caml_ba_get_1
 //Requires: caml_ba_set_1
-//Requires: caml_int64_of_string
-//Requires: caml_new_string
+//Requires: caml_lxm_M
+//Requires: caml_lxm_daba
+//Version: >= 5
 function caml_lxm_next(v) {
   function shift_l(x, k) {
     return caml_int64_shift_left(x, k);
@@ -37,8 +54,8 @@ function caml_lxm_next(v) {
   function set(a, i, x) {
     return caml_ba_set_1(a, i, x);
   }
-  var M = caml_int64_of_string(caml_new_string("0xd1342543de82ef95"));
-  var daba = caml_int64_of_string(caml_new_string("0xdaba0b6eb09322e3"));
+  var M = caml_lxm_M;
+  var daba = caml_lxm_daba;
   var z, q0, q1;
   var st = v;
   var a = get(st, 0);
diff --git a/runtime/runtime_events.js b/runtime/js/runtime_events.js
similarity index 67%
rename from runtime/runtime_events.js
rename to runtime/js/runtime_events.js
index 1811ec9d1..d52a274f0 100644
--- a/runtime/runtime_events.js
+++ b/runtime/js/runtime_events.js
@@ -1,58 +1,89 @@
 //Provides: caml_custom_event_index
+//Version: >= 5.1
 var caml_custom_event_index = 0;
 
 //Provides: caml_runtime_events_user_register
 //Requires: caml_custom_event_index
+//Version: >= 5.1
 function caml_runtime_events_user_register(event_name, event_tag, event_type) {
   caml_custom_event_index += 1;
   return [0, caml_custom_event_index, event_name, event_type, event_tag];
 }
 
 //Provides: caml_runtime_events_user_write
+//Version: >= 5.1
 function caml_runtime_events_user_write(event, event_content) {
   return 0;
 }
 
 //Provides: caml_runtime_events_user_resolve
+//Version: >= 5.0
 function caml_runtime_events_user_resolve() {
   return 0;
 }
 
 //Provides: caml_ml_runtime_events_start
-//Alias: caml_runtime_events_start
+//Version: >= 5.2
 function caml_ml_runtime_events_start() {
   return 0;
 }
 
+//Provides: caml_runtime_events_start
+//Version: >= 5.0, < 5.2
+function caml_runtime_events_start() {
+  return 0;
+}
+
 //Provides: caml_ml_runtime_events_pause
-//Alias: caml_runtime_events_pause
+//Version: >= 5.2
 function caml_ml_runtime_events_pause() {
   return 0;
 }
 
+//Provides: caml_runtime_events_pause
+//Version: >= 5.0, < 5.2
+function caml_runtime_events_pause() {
+  return 0;
+}
+
 //Provides: caml_ml_runtime_events_are_active
 //Version: >= 5.2
 function caml_ml_runtime_events_are_active() {
   return 0;
 }
 
+//Provides: caml_runtime_events_resume
+//Version: >=5.0, < 5.2
+function caml_runtime_events_resume() {
+  return 0;
+}
+
 //Provides: caml_ml_runtime_events_resume
-//Alias: caml_runtime_events_resume
+//Version: >= 5.2
 function caml_ml_runtime_events_resume() {
   return 0;
 }
 
 //Provides: caml_runtime_events_create_cursor
+//Version: >= 5.0
 function caml_runtime_events_create_cursor(target) {
   return {};
 }
 
 //Provides: caml_runtime_events_free_cursor
+//Version: >= 5.0
 function caml_runtime_events_free_cursor(cursor) {
   return 0;
 }
 
 //Provides: caml_runtime_events_read_poll
+//Version: >= 5.0
 function caml_runtime_events_read_poll(cursor, callbacks, num) {
   return 0;
 }
+
+//Provides: caml_ml_runtime_events_path const
+//Version: >= 5.3
+function caml_ml_runtime_events_path(_unit) {
+  return 0;
+}
diff --git a/runtime/stdlib.js b/runtime/js/stdlib.js
similarity index 100%
rename from runtime/stdlib.js
rename to runtime/js/stdlib.js
diff --git a/runtime/stdlib_modern.js b/runtime/js/stdlib_modern.js
similarity index 100%
rename from runtime/stdlib_modern.js
rename to runtime/js/stdlib_modern.js
diff --git a/runtime/str.js b/runtime/js/str.js
similarity index 99%
rename from runtime/str.js
rename to runtime/js/str.js
index e8fa271e4..8c39ee65c 100644
--- a/runtime/str.js
+++ b/runtime/js/str.js
@@ -389,8 +389,3 @@ function re_replacement_text(repl, groups, orig) {
   }
   return caml_string_of_jsbytes(res);
 }
-
-//Provides: caml_str_initialize
-function caml_str_initialize(unit) {
-  return 0;
-}
diff --git a/runtime/sync.js b/runtime/js/sync.js
similarity index 100%
rename from runtime/sync.js
rename to runtime/js/sync.js
diff --git a/runtime/sys.js b/runtime/js/sys.js
similarity index 99%
rename from runtime/sys.js
rename to runtime/js/sys.js
index 466ad111e..c87ccf2a7 100644
--- a/runtime/sys.js
+++ b/runtime/js/sys.js
@@ -337,6 +337,7 @@ function caml_ml_runtime_warnings_enabled(_unit) {
 }
 
 //Provides: caml_spacetime_enabled const (const)
+//Version: < 4.12
 function caml_spacetime_enabled(_unit) {
   return 0;
 }
@@ -347,12 +348,14 @@ function caml_sys_const_naked_pointers_checked(_unit) {
 }
 
 //Provides: caml_register_channel_for_spacetime const (const)
+//Version: < 4.12
 function caml_register_channel_for_spacetime(_channel) {
   return 0;
 }
 
 //Provides: caml_spacetime_only_works_for_native_code
 //Requires: caml_failwith
+//Version: < 4.12
 function caml_spacetime_only_works_for_native_code() {
   caml_failwith("Spacetime profiling only works for native code");
 }
@@ -365,6 +368,7 @@ function caml_xdg_defaults(_unit) {
 
 //Provides: caml_sys_is_regular_file
 //Requires: resolve_fs_device
+//Version: >= 5.1
 function caml_sys_is_regular_file(name) {
   var root = resolve_fs_device(name);
   return root.device.isFile(root.rest);
diff --git a/runtime/toplevel.js b/runtime/js/toplevel.js
similarity index 93%
rename from runtime/toplevel.js
rename to runtime/js/toplevel.js
index b0e9f0599..9d54018f8 100644
--- a/runtime/toplevel.js
+++ b/runtime/js/toplevel.js
@@ -17,22 +17,6 @@
 // along with this program; if not, write to the Free Software
 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
-//Provides: caml_terminfo_setup
-function caml_terminfo_setup() {
-  return 1;
-} // Bad_term
-//Provides: caml_terminfo_backup
-function caml_terminfo_backup() {
-  return 0;
-}
-//Provides: caml_terminfo_standout
-function caml_terminfo_standout() {
-  return 0;
-}
-//Provides: caml_terminfo_resume
-function caml_terminfo_resume() {
-  return 0;
-}
 //Provides: caml_terminfo_rows
 function caml_terminfo_rows() {
   return 0;
@@ -151,11 +135,13 @@ function caml_static_release_bytecode() {
 
 //Provides: caml_static_alloc
 //Requires: caml_create_bytes
+//Version: < 4.12
 function caml_static_alloc(len) {
   return caml_create_bytes(len);
 }
 
 //Provides: caml_static_free
+//Version: < 4.12
 function caml_static_free() {
   return 0;
 }
diff --git a/runtime/unix.js b/runtime/js/unix.js
similarity index 100%
rename from runtime/unix.js
rename to runtime/js/unix.js
diff --git a/runtime/weak.js b/runtime/js/weak.js
similarity index 100%
rename from runtime/weak.js
rename to runtime/js/weak.js
diff --git a/runtime/zstd.js b/runtime/js/zstd.js
similarity index 100%
rename from runtime/zstd.js
rename to runtime/js/zstd.js
diff --git a/runtime/zstd.ts b/runtime/js/zstd.ts
similarity index 100%
rename from runtime/zstd.ts
rename to runtime/js/zstd.ts