diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c
index 82ff31273b..f89745f063 100644
--- a/src/backend/optimizer/path/pathkeys.c
+++ b/src/backend/optimizer/path/pathkeys.c
@@ -369,6 +369,7 @@ group_keys_reorder_by_pathkeys(List *pathkeys, List **group_pathkeys,
 {
 	List	   *new_group_pathkeys = NIL,
 			   *new_group_clauses = NIL;
+	List	   *grouping_pathkeys = list_copy_head(*group_pathkeys, num_groupby_pathkeys);
 	ListCell   *lc;
 	int			n;
 
@@ -395,7 +396,7 @@ group_keys_reorder_by_pathkeys(List *pathkeys, List **group_pathkeys,
 		 * there is no sortclause reference for some reason.
 		 */
 		if (foreach_current_index(lc) >= num_groupby_pathkeys ||
-			!list_member_ptr(*group_pathkeys, pathkey) ||
+			!list_member_ptr(grouping_pathkeys, pathkey) ||
 			pathkey->pk_eclass->ec_sortref == 0)
 			break;
 
@@ -429,6 +430,7 @@ group_keys_reorder_by_pathkeys(List *pathkeys, List **group_pathkeys,
 	*group_clauses = list_concat_unique_ptr(new_group_clauses,
 											*group_clauses);
 
+	pfree(grouping_pathkeys);
 	return n;
 }