diff --git a/contrib/hstore_plpython/expected/hstore_plpython.out b/contrib/hstore_plpython/expected/hstore_plpython.out
index b7a6a92ac6f..243482374b9 100644
--- a/contrib/hstore_plpython/expected/hstore_plpython.out
+++ b/contrib/hstore_plpython/expected/hstore_plpython.out
@@ -53,19 +53,29 @@ SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
 (1 row)
 
 -- test python -> hstore
-CREATE FUNCTION test2() RETURNS hstore
+CREATE FUNCTION test2(a int, b text) RETURNS hstore
 LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
-val = {'a': 1, 'b': 'boo', 'c': None}
+val = {'a': a, 'b': b, 'c': None}
 return val
 $$;
-SELECT test2();
+SELECT test2(1, 'boo');
               test2              
 ---------------------------------
  "a"=>"1", "b"=>"boo", "c"=>NULL
 (1 row)
 
+--- test ruleutils
+\sf test2
+CREATE OR REPLACE FUNCTION public.test2(a integer, b text)
+ RETURNS hstore
+ TRANSFORM FOR TYPE hstore
+ LANGUAGE plpythonu
+AS $function$
+val = {'a': a, 'b': b, 'c': None}
+return val
+$function$
 -- test python -> hstore[]
 CREATE FUNCTION test2arr() RETURNS hstore[]
 LANGUAGE plpythonu
diff --git a/contrib/hstore_plpython/sql/hstore_plpython.sql b/contrib/hstore_plpython/sql/hstore_plpython.sql
index 9ff2ebcd833..6d4a8f3a587 100644
--- a/contrib/hstore_plpython/sql/hstore_plpython.sql
+++ b/contrib/hstore_plpython/sql/hstore_plpython.sql
@@ -45,15 +45,18 @@ SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
 
 
 -- test python -> hstore
-CREATE FUNCTION test2() RETURNS hstore
+CREATE FUNCTION test2(a int, b text) RETURNS hstore
 LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
-val = {'a': 1, 'b': 'boo', 'c': None}
+val = {'a': a, 'b': b, 'c': None}
 return val
 $$;
 
-SELECT test2();
+SELECT test2(1, 'boo');
+
+--- test ruleutils
+\sf test2
 
 
 -- test python -> hstore[]
diff --git a/src/backend/utils/fmgr/funcapi.c b/src/backend/utils/fmgr/funcapi.c
index 10c957ed90c..cc545e20502 100644
--- a/src/backend/utils/fmgr/funcapi.c
+++ b/src/backend/utils/fmgr/funcapi.c
@@ -935,7 +935,9 @@ get_func_arg_info(HeapTuple procTup,
 /*
  * get_func_trftypes
  *
- * Returns the number of transformed types used by function.
+ * Returns the number of transformed types used by the function.
+ * If there are any, a palloc'd array of the type OIDs is returned
+ * into *p_trftypes.
  */
 int
 get_func_trftypes(HeapTuple procTup,
@@ -964,7 +966,6 @@ get_func_trftypes(HeapTuple procTup,
 			ARR_HASNULL(arr) ||
 			ARR_ELEMTYPE(arr) != OIDOID)
 			elog(ERROR, "protrftypes is not a 1-D Oid array");
-		Assert(nelems >= ((Form_pg_proc) GETSTRUCT(procTup))->pronargs);
 		*p_trftypes = (Oid *) palloc(nelems * sizeof(Oid));
 		memcpy(*p_trftypes, ARR_DATA_PTR(arr),
 			   nelems * sizeof(Oid));