diff --git a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Form/AjaxTestDialogForm.php b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Form/AjaxTestDialogForm.php
index eba241f..9d598d8 100644
--- a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Form/AjaxTestDialogForm.php
+++ b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Form/AjaxTestDialogForm.php
@@ -92,13 +92,13 @@ public function nonModal(&$form, &$form_state) {
    * @param bool $is_modal
    *   (optional) TRUE if modal, FALSE if plain dialog. Defaults to FALSE.
    *
-   * @return AjaxResponse
+   * @return \Drupal\Core\Ajax\AjaxResponse
    *   An ajax response object.
    */
   protected function dialog($is_modal = FALSE) {
     $content = ajax_test_dialog_contents();
     $response = new AjaxResponse();
-    $title = $this->t(String::checkPlain('AJAX Dialog contents'));
+    $title = $this->t('AJAX Dialog contents');
     $html = drupal_render($content);
     if ($is_modal) {
       $response->addCommand(new OpenModalDialogCommand($title, $html));
@@ -110,4 +110,4 @@ protected function dialog($is_modal = FALSE) {
     return $response;
   }
 
-}
\ No newline at end of file
+}