diff --git a/src/Symfony/Foundation/Bundle/KernelBundle.php b/src/Symfony/Foundation/Bundle/KernelBundle.php
index 59a4069a99..5f2b39eb2b 100644
--- a/src/Symfony/Foundation/Bundle/KernelBundle.php
+++ b/src/Symfony/Foundation/Bundle/KernelBundle.php
@@ -41,7 +41,7 @@ class KernelBundle extends Bundle
       $configuration->setDefinition('event_dispatcher', $configuration->findDefinition('debug.event_dispatcher'));
     }
 
-    $container->merge($configuration);
+    return $configuration;
   }
 
   public function boot(ContainerInterface $container)
diff --git a/src/Symfony/Foundation/bootstrap.php b/src/Symfony/Foundation/bootstrap.php
index 55c9a70c6f..1f64e49b1d 100644
--- a/src/Symfony/Foundation/bootstrap.php
+++ b/src/Symfony/Foundation/bootstrap.php
@@ -63,7 +63,7 @@ class KernelBundle extends Bundle
       $configuration->setDefinition('event_dispatcher', $configuration->findDefinition('debug.event_dispatcher'));
     }
 
-    $container->merge($configuration);
+    return $configuration;
   }
 
   public function boot(ContainerInterface $container)