diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index a4b379987b..f3c390928b 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -1409,7 +1409,6 @@ contain_leaked_vars_walker(Node *node, void *context)
 		case T_ScalarArrayOpExpr:
 		case T_CoerceViaIO:
 		case T_ArrayCoerceExpr:
-		case T_SubscriptingRef:
 
 			/*
 			 * If node contains a leaky function call, and there's any Var
@@ -1421,6 +1420,23 @@ contain_leaked_vars_walker(Node *node, void *context)
 				return true;
 			break;
 
+		case T_SubscriptingRef:
+			{
+				SubscriptingRef *sbsref = (SubscriptingRef *) node;
+
+				/*
+				 * subscripting assignment is leaky, but subscripted fetches
+				 * are not
+				 */
+				if (sbsref->refassgnexpr != NULL)
+				{
+					/* Node is leaky, so reject if it contains Vars */
+					if (contain_var_clause(node))
+						return true;
+				}
+			}
+			break;
+
 		case T_RowCompareExpr:
 			{
 				/*