diff --git a/src/Symfony/Components/DependencyInjection/BuilderConfiguration.php b/src/Symfony/Components/DependencyInjection/BuilderConfiguration.php
index 512f76849a..7da14fb9bf 100644
--- a/src/Symfony/Components/DependencyInjection/BuilderConfiguration.php
+++ b/src/Symfony/Components/DependencyInjection/BuilderConfiguration.php
@@ -277,7 +277,7 @@ class BuilderConfiguration
   {
     unset($this->aliases[$id]);
 
-    return $this->definitions[$id] = $definition;
+    $this->definitions[$id] = $definition;
 
     return $this;
   }