diff --git a/core/includes/menu.inc b/core/includes/menu.inc
index c02e4f7..bbf5c43 100644
--- a/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -2701,10 +2701,11 @@ function menu_link_rebuild_defaults() {
     }
   }
 
-  // Find any item whose router path does not exist any more.
+  // Find any item whose entry in hook_menu_link_defaults() no longer exists.
   if ($all_links) {
     $query = \Drupal::entityQuery('menu_link')
       ->condition('machine_name', array_keys($all_links), 'NOT IN')
+      ->condition('machine_name', NULL, '<>')
       ->condition('external', 0)
       ->condition('updated', 0)
       ->condition('customized', 0)
@@ -2717,7 +2718,7 @@ function menu_link_rebuild_defaults() {
 
   // Remove all such items. Starting from those with the greatest depth will
   // minimize the amount of re-parenting done by the menu link controller.
-  if (!empty($result)) {
+  if ($result) {
     menu_link_delete_multiple($result, TRUE);
   }
 }