diff --git a/core/modules/system/tests/modules/form_test/form_test.module b/core/modules/system/tests/modules/form_test/form_test.module
index e25a16e..1593888 100644
--- a/core/modules/system/tests/modules/form_test/form_test.module
+++ b/core/modules/system/tests/modules/form_test/form_test.module
@@ -5,6 +5,8 @@
  * Helper module for the form API tests.
  */
 
+use Symfony\Component\HttpFoundation\JsonResponse;
+
 /**
  * Implements hook_menu().
  */
@@ -1441,8 +1443,7 @@ function form_test_color($form, &$form_state) {
  * Form submission handler for form_test_color().
  */
 function form_test_color_submit($form, &$form_state) {
-  drupal_json_output($form_state['values']);
-  exit;
+  return new JsonResponse($form_state['values']);
 }
 
 /**