diff --git a/core/includes/menu.inc b/core/includes/menu.inc
index b928a26..b50d90a 100644
--- a/core/includes/menu.inc
+++ b/core/includes/menu.inc
@@ -753,6 +753,12 @@ function _menu_translate(&$router_item, $map, $to_arg = FALSE) {
     $tab_parent_map = explode('/', $router_item['tab_parent']);
   }
   for ($i = 0; $i < $router_item['number_parts']; $i++) {
+    // data may not be aligned, like menu_router item 'node/%/edit/add/%/%'.
+    if (!isset($path_map[$i])) {
+//      dpm(debug_backtrace());
+//      continue;
+    }
+
     if ($link_map[$i] == '%') {
       $link_map[$i] = $path_map[$i];
     }