diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php b/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php
index d4377f0..87ece21 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php
@@ -665,7 +665,7 @@ function build_group_validate($form, &$form_state) {
   /**
    * Save new group items, re-enumerates and remove groups marked to delete.
    */
-  function buildGroupSubmit($form, &$form_state) {
+  protected function buildGroupSubmit($form, &$form_state) {
     $groups = array();
     uasort($form_state['values']['options']['group_info']['group_items'], 'drupal_sort_weight');
     // Filter out removed items.