diff --git a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestForm.php b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestForm.php
index 582ad05..7fda5c6 100644
--- a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestForm.php
+++ b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestForm.php
@@ -26,8 +26,7 @@ public function getFormID() {
    */
   public function buildForm(array $form, array &$form_state) {
 
-    drupal_set_title($this->t('Ajax Form contents'));
-
+    $form['#title'] = $this->t('Ajax Form contents');
     $form['#action'] = url('ajax-test/dialog');
     $form['#cache'] = TRUE;