diff --git a/core/lib/Drupal/Core/AjaxController.php b/core/lib/Drupal/Core/AjaxController.php
index c423489..9e92ac2 100644
--- a/core/lib/Drupal/Core/AjaxController.php
+++ b/core/lib/Drupal/Core/AjaxController.php
@@ -12,6 +12,8 @@
 use Drupal\Core\Ajax\PrependCommand;
 use Symfony\Component\DependencyInjection\ContainerAware;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Default controller for ajax requests.
@@ -80,6 +82,7 @@ public function content(Request $request, $_content) {
           $response->addCommand(new PrependCommand(NULL, $status_messages));
         }
       }
+      $response->prepare($request);
     }
     return $response;
   }