diff --git a/core/modules/system/tests/modules/session_test/session_test.module b/core/modules/system/tests/modules/session_test/session_test.module
index 9120c41..c113aa6 100644
--- a/core/modules/system/tests/modules/session_test/session_test.module
+++ b/core/modules/system/tests/modules/session_test/session_test.module
@@ -1,5 +1,7 @@
 <?php
 
+use Symfony\Component\HttpFoundation\Response;
+
 /**
  * Implements hook_user_login().
  */
@@ -7,7 +9,7 @@ function session_test_user_login($account) {
   if ($account->getUsername() == 'session_test_user') {
     // Exit so we can verify that the session was regenerated
     // before hook_user() was called.
-    return new Response('OK', 200);
+    return new Response('OK', Response::HTTP_OK );
   }
 }