diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index b399592ff8..33df9b0783 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -2771,6 +2771,7 @@ get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel)
 		{
 			PathKey    *pathkey = (PathKey *) lfirst(lc);
 			EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
+			Expr	   *em_expr;
 
 			/*
 			 * We can only build an Incremental Sort for pathkeys which
@@ -2783,7 +2784,8 @@ get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel)
 			 * enable not just an incremental sort on the entirety of
 			 * query_pathkeys but also incremental sort below a JOIN.
 			 */
-			if (!find_em_expr_for_rel(pathkey_ec, rel))
+			if (!(em_expr = find_em_expr_for_rel(pathkey_ec, rel)) ||
+				contain_mutable_functions((Node *) em_expr))
 				break;
 
 			npathkeys++;