diff --git a/core/modules/block/lib/Drupal/block/BlockListController.php b/core/modules/block/lib/Drupal/block/BlockListController.php
index b210574..17d7b8e 100644
--- a/core/modules/block/lib/Drupal/block/BlockListController.php
+++ b/core/modules/block/lib/Drupal/block/BlockListController.php
@@ -147,6 +147,7 @@ public function buildForm(array $form, array &$form_state) {
     $form['#attached']['library'][] = array('system', 'drupal.tableheader');
     $form['#attached']['library'][] = array('block', 'drupal.block');
     $form['#attached']['library'][] = array('block', 'drupal.block.admin');
+    $form['#attached']['library'][] = array('system', 'drupal.ajax');
     $form['#attributes']['class'][] = 'clearfix';
 
     // Add a last region for disabled blocks.