diff --git a/core/modules/ckeditor/lib/Drupal/ckeditor/Plugin/Editor/CKEditor.php b/core/modules/ckeditor/lib/Drupal/ckeditor/Plugin/Editor/CKEditor.php
index 0465cdf..92dc6fb 100644
--- a/core/modules/ckeditor/lib/Drupal/ckeditor/Plugin/Editor/CKEditor.php
+++ b/core/modules/ckeditor/lib/Drupal/ckeditor/Plugin/Editor/CKEditor.php
@@ -171,7 +171,7 @@ public function settingsForm(array $form, array &$form_state, EditorEntity $edit
     // Build a fake Editor object, which we'll use to generate JavaScript
     // settings for this fake Editor instance.
     $fake_editor = entity_create('editor', array(
-      'format' => '',
+      'format' => 'plain_text',
       'editor' => 'ckeditor',
       'settings' => array(
         // Single toolbar row that contains all existing buttons.