diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 12e9ed0d0c7..4b9b5d563f6 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1635,9 +1635,14 @@ restrict_infos_logically_equal(RestrictInfo *a, RestrictInfo *b)
 	int			saved_rinfo_serial = a->rinfo_serial;
 	bool		result;
 
-	a->rinfo_serial = b->rinfo_serial;
-	result = equal(a, b);
-	a->rinfo_serial = saved_rinfo_serial;
+	if (bms_membership(a->required_relids) == BMS_SINGLETON)
+		result = equal(a->clause, b->clause);
+	else
+	{
+		a->rinfo_serial = b->rinfo_serial;
+		result = equal(a, b);
+		a->rinfo_serial = saved_rinfo_serial;
+	}
 
 	return result;
 }
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index fe89754a73c..2ad663c952a 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -744,6 +744,12 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
 bool
 ChangeVarNodesWalkExpression(Node *node, ChangeVarNodes_context *context)
 {
+	if (node == NULL)
+		return false;
+
+	if (ChangeVarNodes_walker(node, context))
+		return true;
+
 	return expression_tree_walker(node,
 								  ChangeVarNodes_walker,
 								  (void *) context);