diff --git a/NEWS.md b/NEWS.md
index 4d0fc911569..b1f211a8ae7 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -60,6 +60,7 @@ milestone for 4.0.0
 * _pgr_dijkstra(text,anyarray,anyarray,boolean,boolean,boolean,bigint)
 * _pgr_dijkstra(text,text,boolean,boolean,boolean)
 * _pgr_drivingdistance(text,anyarray,double precision,boolean,boolean)
+* _pgr_prim(text,anyarray,text,bigint,double precision)
 * _pgr_trsp(text,integer,double precision,integer,double precision,boolean,boolean,text)
 * _pgr_trsp(text,text,anyarray,anyarray,boolean)
 * _pgr_trsp(text,text,anyarray,bigint,boolean)
@@ -74,6 +75,7 @@ milestone for 4.0.0
 **Deprecation of internal C/C++ functions**
 
 * _pgr_drivingdistance(text,anyarray,double precision,boolean,boolean)
+* _pgr_prim(text,anyarray,text,bigint,double precision)
 
 **Internal C/C++ functions in legacy**
 
diff --git a/doc/src/release_notes.rst b/doc/src/release_notes.rst
index 6001b557244..5f80e3c95ae 100644
--- a/doc/src/release_notes.rst
+++ b/doc/src/release_notes.rst
@@ -91,6 +91,7 @@ milestone for 4.0.0
 * _pgr_dijkstra(text,anyarray,anyarray,boolean,boolean,boolean,bigint)
 * _pgr_dijkstra(text,text,boolean,boolean,boolean)
 * _pgr_drivingdistance(text,anyarray,double precision,boolean,boolean)
+* _pgr_prim(text,anyarray,text,bigint,double precision)
 * _pgr_trsp(text,integer,double precision,integer,double precision,boolean,boolean,text)
 * _pgr_trsp(text,text,anyarray,anyarray,boolean)
 * _pgr_trsp(text,text,anyarray,bigint,boolean)
@@ -105,6 +106,7 @@ milestone for 4.0.0
 .. rubric:: Deprecation of internal C/C++ functions
 
 * _pgr_drivingdistance(text,anyarray,double precision,boolean,boolean)
+* _pgr_prim(text,anyarray,text,bigint,double precision)
 
 .. rubric:: Internal C/C++ functions in legacy
 
diff --git a/sql/sigs/pgrouting--4.0.sig b/sql/sigs/pgrouting--4.0.sig
index 4cc42d208d8..942756b0e91 100644
--- a/sql/sigs/pgrouting--4.0.sig
+++ b/sql/sigs/pgrouting--4.0.sig
@@ -245,7 +245,6 @@ pgr_primdd(text,bigint,numeric)
 pgr_primdfs(text,anyarray,bigint)
 pgr_primdfs(text,bigint,bigint)
 pgr_prim(text)
-_pgr_prim(text,anyarray,text,bigint,double precision)
 _pgr_primv4(text,anyarray,text,bigint,double precision)
 pgr_pushrelabel(text,anyarray,anyarray)
 pgr_pushrelabel(text,anyarray,bigint)
diff --git a/sql/spanningTree/_prim.sql b/sql/spanningTree/_prim.sql
index 3401e2812d8..9da3da2593a 100644
--- a/sql/spanningTree/_prim.sql
+++ b/sql/spanningTree/_prim.sql
@@ -27,18 +27,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
  ********************************************************************PGR-GNU*/
 
-----------
-----------
--- mst
-----------
-----------
-
-
-----------------
--- _pgr_prim
-----------------
-
-
 --v3.7
 CREATE FUNCTION _pgr_primv4(
   TEXT,     -- Edge sql
@@ -61,30 +49,3 @@ LANGUAGE C VOLATILE STRICT;
 
 COMMENT ON FUNCTION _pgr_primv4(TEXT, ANYARRAY, TEXT, BIGINT, FLOAT)
 IS 'pgRouting internal function';
-
---v3.0
-CREATE FUNCTION _pgr_prim(
-    TEXT,             -- Edge sql
-    ANYARRAY,         -- tree root for traversal
-    order_by TEXT,
-    max_depth BIGINT,
-    distance FLOAT,
-
-    OUT seq BIGINT,
-    OUT depth BIGINT,
-    OUT start_vid BIGINT,
-    OUT node BIGINT,
-    OUT edge BIGINT,
-    OUT cost FLOAT,
-    OUT agg_cost FLOAT)
-RETURNS SETOF RECORD AS
-'MODULE_PATHNAME'
-LANGUAGE C VOLATILE STRICT;
-
-
--- COMMENTS
-
-
-COMMENT ON FUNCTION _pgr_prim(TEXT, ANYARRAY, TEXT, BIGINT, FLOAT)
-IS 'pgRouting internal function deprecated on v3.7.0';
-
diff --git a/src/spanningTree/prim.c b/src/spanningTree/prim.c
index 93071398f3b..141ae580f6a 100644
--- a/src/spanningTree/prim.c
+++ b/src/spanningTree/prim.c
@@ -171,7 +171,11 @@ PGDLLEXPORT Datum _pgr_primv4(PG_FUNCTION_ARGS) {
     }
 }
 
-/******************************************************************************/
+/* Deprecated code starts here
+ * This code is used on v3.6 and under
+ *
+ * TODO(v5) Move to legacy
+ */
 
 PGDLLEXPORT Datum _pgr_prim(PG_FUNCTION_ARGS);
 PG_FUNCTION_INFO_V1(_pgr_prim);
@@ -183,6 +187,12 @@ PGDLLEXPORT Datum _pgr_prim(PG_FUNCTION_ARGS) {
     MST_rt *result_tuples = NULL;
     size_t result_count = 0;
 
+    ereport(NOTICE, (
+            errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+            errmsg("A stored procedure is using deprecated C internal function '%s'", __func__),
+            errdetail("Library function '%s' was deprecated in pgRouting %s", __func__, "3.7.0"),
+            errhint("Consider upgrade pgRouting")));
+
     if (SRF_IS_FIRSTCALL()) {
         MemoryContext   oldcontext;
         funcctx = SRF_FIRSTCALL_INIT();