diff --git a/src/Symfony/Bundle/TwigBundle/Resources/config/mailer.xml b/src/Symfony/Bundle/TwigBundle/Resources/config/mailer.xml
index d61bc32c45..0e425952ff 100644
--- a/src/Symfony/Bundle/TwigBundle/Resources/config/mailer.xml
+++ b/src/Symfony/Bundle/TwigBundle/Resources/config/mailer.xml
@@ -6,8 +6,9 @@
 
     <services>
         <service id="twig.mailer.message_listener" class="Symfony\Component\Mailer\EventListener\MessageListener">
-            <argument />
+            <argument>null</argument>
             <argument type="service" id="twig.mime_body_renderer" />
+            <tag name="kernel.event_subscriber"/>
         </service>
 
         <service id="twig.mime_body_renderer" class="Symfony\Bridge\Twig\Mime\BodyRenderer">