diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 76dad17e33..f2f4a33dc8 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -402,14 +402,12 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
  *	  Find a base or otherrel relation entry, which must already exist.
  */
 RelOptInfo *
-find_base_rel(PlannerInfo *root, int relid)
+find_base_rel(const PlannerInfo *root, int relid)
 {
-	RelOptInfo *rel;
-
-	Assert(relid > 0);
-
-	if (relid < root->simple_rel_array_size)
+	if ((uint32) relid < (uint32) root->simple_rel_array_size)
 	{
+		RelOptInfo *rel;
+
 		rel = root->simple_rel_array[relid];
 		if (rel)
 			return rel;
@@ -430,11 +428,9 @@ find_base_rel(PlannerInfo *root, int relid)
  * outer joins.
  */
 RelOptInfo *
-find_base_rel_ignore_join(PlannerInfo *root, int relid)
+find_base_rel_ignore_join(const PlannerInfo *root, int relid)
 {
-	Assert(relid > 0);
-
-	if (relid < root->simple_rel_array_size)
+	if ((uint32) relid < (uint32) root->simple_rel_array_size)
 	{
 		RelOptInfo *rel;
 		RangeTblEntry *rte;
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 6e557bebc4..5295175fa3 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -306,8 +306,8 @@ extern void setup_simple_rel_arrays(PlannerInfo *root);
 extern void expand_planner_arrays(PlannerInfo *root, int add_size);
 extern RelOptInfo *build_simple_rel(PlannerInfo *root, int relid,
 									RelOptInfo *parent);
-extern RelOptInfo *find_base_rel(PlannerInfo *root, int relid);
-extern RelOptInfo *find_base_rel_ignore_join(PlannerInfo *root, int relid);
+extern RelOptInfo *find_base_rel(const PlannerInfo *root, int relid);
+extern RelOptInfo *find_base_rel_ignore_join(const PlannerInfo *root, int relid);
 extern RelOptInfo *find_join_rel(PlannerInfo *root, Relids relids);
 extern RelOptInfo *build_join_rel(PlannerInfo *root,
 								  Relids joinrelids,