diff --git a/src/lib/builtins.pl b/src/lib/builtins.pl
index bea783f77..f4d9df79d 100644
--- a/src/lib/builtins.pl
+++ b/src/lib/builtins.pl
@@ -3,12 +3,12 @@
                      at_end_of_stream/0, at_end_of_stream/1,
                      atom_chars/2, atom_codes/2, atom_concat/3,
                      atom_length/2, bagof/3, call/1, call/2, call/3,
-                     call/4, call/5, call/6, call/7, call/8, call/9,
+                     call/4, call/5, call/6, call/7, call/8,
                      callable/1, catch/3, char_code/2, clause/2,
                      close/1, close/2, current_input/1,
                      current_output/1, current_op/3,
                      current_predicate/1, current_prolog_flag/2,
-                     error/2, fail/0, false/0, findall/3, findall/4,
+                     fail/0, false/0, findall/3,
                      flush_output/0, flush_output/1, get_byte/1,
                      get_byte/2, get_char/1, get_char/2, get_code/1,
                      get_code/2, halt/0, halt/1, nl/0, nl/1,
@@ -53,7 +53,7 @@
 false :- '$fail'.
 
 
-% These are stub versions of call/{1-9} defined for bootstrapping.
+% These are stub versions of call/{1-8} defined for bootstrapping.
 % Once Scryer is bootstrapped, each is replaced with a version that
 % uses expand_goal to pass the expanded goal along to '$call'.
 
@@ -106,12 +106,6 @@
 % appended to the argument list.
 call(_, _, _, _, _, _, _, _).
 
-%% call(Goal, ExtraArg1, ExtraArg2, ExtraArg3, ExtraArg4, ExtraArg5, ExtraArg6, ExtraArg7, ExtraArg8).
-%
-% Execute Goal with ExtraArg1, ExtraArg2, ExtraArg3, ExtraArg4, ExtraArg5, ExtraArg6, ExtraArg7 and
-% ExtraArg8, appended to the argument list.
-call(_, _, _, _, _, _, _, _, _).
-
 
 :- meta_predicate catch(0, ?, 0).
 
@@ -927,23 +921,6 @@
     '$get_lh_from_offset_diff'(LhOffset, Solutions0, Solutions1).
 
 
-:- meta_predicate findall(?, 0, ?, ?).
-
-:- non_counted_backtracking findall/4.
-
-%% findall(Template, Goal, Solutions0, Solutions1)
-%
-% Similar to `findall/3` but returns the solutions as the difference list Solutions0-Solutions1.
-findall(Template, Goal, Solutions0, Solutions1) :-
-    error:can_be(list, Solutions0),
-    error:can_be(list, Solutions1),
-    '$lh_length'(LhLength),
-    catch(builtins:'$iterate_find_all_diff'(Template, Goal, Solutions0,
-                                            Solutions1, LhLength),
-          Error,
-          builtins:findall_cleanup(LhLength, Error)
-         ).
-
 :- non_counted_backtracking set_difference/3.
 
 set_difference([X|Xs], [Y|Ys], Zs) :-
@@ -2241,12 +2218,3 @@
 % Writes a new line character to the stream Stream.
 nl(Stream) :-
     put_char(Stream, '\n').
-
-%% error(ErrorTerm, ImpDef).
-%
-% Throws an exception of the following structure: `error(ErrorTerm, ImpDef)`.
-error(Error_term, Imp_def) :-
-    (  var(Error_term) ->
-       throw(error(instantiation_error, error/2))
-    ;  throw(error(Error_term, Imp_def))
-    ).
diff --git a/src/lib/error.pl b/src/lib/error.pl
index 67df8a32f..b6e685e32 100644
--- a/src/lib/error.pl
+++ b/src/lib/error.pl
@@ -8,7 +8,8 @@
                   instantiation_error/1,
                   domain_error/3,
                   type_error/3,
-                  call_with_error_context/2
+                  call_with_error_context/2,
+                  error/2
                   ]).
 
 
@@ -217,6 +218,15 @@
    Shorthands for throwing ISO errors.
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
+%% error(ErrorTerm, ImpDef).
+%
+% Throws an exception of the following structure: `error(ErrorTerm, ImpDef)`.
+error(Error_term, Imp_def) :-
+    (  var(Error_term) ->
+       throw(error(instantiation_error, error/2))
+    ;  throw(error(Error_term, Imp_def))
+    ).
+
 instantiation_error(Context) :-
     throw(error(instantiation_error, Context)).
 
diff --git a/src/lib/iso_ext.pl b/src/lib/iso_ext.pl
index 5c779b10e..1af06cc52 100644
--- a/src/lib/iso_ext.pl
+++ b/src/lib/iso_ext.pl
@@ -11,6 +11,7 @@
                     call_with_inference_limit/3,
                     call_residue_vars/2,
                     forall/2,
+                    findall/4,
                     partial_string/1,
                     partial_string/3,
                     partial_string_tail/2,
@@ -381,6 +382,24 @@
                        ;   true
                        )).
 
+%% findall(Template, Goal, Solutions0, Solutions1)
+%
+% Similar to `findall/3` but returns the solutions as the difference list Solutions0-Solutions1.
+
+:- meta_predicate findall(?, 0, ?, ?).
+
+:- non_counted_backtracking findall/4.
+
+findall(Template, Goal, Solutions0, Solutions1) :-
+    error:can_be(list, Solutions0),
+    error:can_be(list, Solutions1),
+    '$lh_length'(LhLength),
+    catch(builtins:'$iterate_find_all_diff'(Template, Goal, Solutions0,
+                                            Solutions1, LhLength),
+          Error,
+          builtins:findall_cleanup(LhLength, Error)
+         ).
+
 %% copy_term_nat(Source, Dest)
 %
 % Similar to `copy_term/2` but without attribute variables