diff --git a/src/Symfony/Component/Security/Core/Authentication/Token/NullToken.php b/src/Symfony/Component/Security/Core/Authentication/Token/NullToken.php
index f6a36561c19b3..1b30d5a7ccda6 100644
--- a/src/Symfony/Component/Security/Core/Authentication/Token/NullToken.php
+++ b/src/Symfony/Component/Security/Core/Authentication/Token/NullToken.php
@@ -33,7 +33,7 @@ public function getCredentials()
 
     public function getUser()
     {
-        return '';
+        return null;
     }
 
     public function setUser($user)