diff --git a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php
index defeaf3..07284ff 100644
--- a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php
+++ b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/Controller/AjaxTestController.php
@@ -51,7 +51,7 @@ public function dialog() {
     $build['dialog_wrappers'] = array('#markup' => '<div id="ajax-test-dialog-wrapper-1"></div><div id="ajax-test-dialog-wrapper-2"></div>');
 
     // Dialog behavior applied to a button.
-    $build['form'] = drupal_get_form('Drupal\ajax_test\Form\AjaxTestDialogForm');
+    $build['form'] = \Drupal::formBuilder()->getForm('Drupal\ajax_test\Form\AjaxTestDialogForm');
 
     // Dialog behavior applied to a #type => 'link'.
     $build['link'] = array(