diff --git a/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/Factory/HttpDigestFactory.php b/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/Factory/HttpDigestFactory.php
index 2f09be07afc75..3a49b5dcdc583 100644
--- a/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/Factory/HttpDigestFactory.php
+++ b/src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/Factory/HttpDigestFactory.php
@@ -62,7 +62,7 @@ public function addConfiguration(NodeDefinition $node)
             ->children()
                 ->scalarNode('provider')->end()
                 ->scalarNode('realm')->defaultValue('Secured Area')->end()
-                ->scalarNode('key')->cannotBeEmpty()->end()
+                ->scalarNode('key')->isRequired()->cannotBeEmpty()->end()
             ->end()
         ;
     }