diff --git a/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorAdminTest.php b/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorAdminTest.php
index f984160..4b2e086 100644
--- a/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorAdminTest.php
+++ b/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorAdminTest.php
@@ -163,6 +163,7 @@ function testAdmin() {
     // Now enable the ckeditor_test module, which provides one configurable
     // CKEditor plugin — this should not affect the Editor config entity.
     \Drupal::moduleHandler()->install(array('ckeditor_test'));
+    $this->rebuildContainer();
     $this->container->get('plugin.manager.ckeditor.plugin')->clearCachedDefinitions();
     $this->drupalGet('admin/config/content/formats/manage/filtered_html');
     $ultra_llama_mode_checkbox = $this->xpath('//input[@type="checkbox" and @name="editor[settings][plugins][llama_contextual_and_button][ultra_llama_mode]" and not(@checked)]');