diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index d2470b7c6a..f3786dd2b6 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -3805,9 +3805,9 @@ reorder_function_arguments(List *args, HeapTuple func_tuple)
 	int			i;
 
 	Assert(nargsprovided <= pronargs);
-	if (pronargs > FUNC_MAX_ARGS)
+	if (pronargs < 0 || pronargs > FUNC_MAX_ARGS)
 		elog(ERROR, "too many function arguments");
-	MemSet(argarray, 0, pronargs * sizeof(Node *));
+	memset(argarray, 0, pronargs * sizeof(Node *));
 
 	/* Deconstruct the argument list into an array indexed by argnumber */
 	i = 0;