diff --git b/core/modules/system/tests/modules/form_test/lib/Drupal/form_test/Controller/FormTestController.php a/core/modules/system/tests/modules/form_test/lib/Drupal/form_test/Controller/FormTestController.php
index 9234bd6..f9bf52c 100644
--- b/core/modules/system/tests/modules/form_test/lib/Drupal/form_test/Controller/FormTestController.php
+++ a/core/modules/system/tests/modules/form_test/lib/Drupal/form_test/Controller/FormTestController.php
@@ -51,8 +51,8 @@ public function wrapperCallback($form_id) {
    */
   public function twoIdenticalFormInstances() {
     return array(
-      'form1' => drupal_get_form(new \Drupal\form_test\Form\FormTestHtmlIdForm()),
-      'form2' => drupal_get_form(new \Drupal\form_test\Form\FormTestHtmlIdForm()),
+      'form1' => drupal_get_form(new FormTestHtmlIdForm()),
+      'form2' => drupal_get_form(new FormTestHtmlIdForm()),
     );
   }