diff --git a/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php b/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
index eb38911c35..2596b4e19a 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
@@ -50,10 +50,10 @@ class MergeExtensionConfigurationPass implements CompilerPassInterface
             $extension->load($config, $tmpContainer);
 
             $container->merge($tmpContainer);
+            $container->getParameterBag()->add($parameters);
         }
 
         $container->addDefinitions($definitions);
         $container->addAliases($aliases);
-        $container->getParameterBag()->add($parameters);
     }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
new file mode 100644
index 0000000000..c16c4c5570
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Tests\Compiler;
+
+use Symfony\Component\DependencyInjection\Compiler\MergeExtensionConfigurationPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Extension\ExtensionInterface;
+
+class MergeExtensionConfigurationPassTest extends \PHPUnit_Framework_TestCase
+{
+    public function testUserParametersAreMostImportantThanDefaultOne()
+    {
+        $container = new ContainerBuilder();
+        $container->getParameterBag()->set('key', 'user_value');
+        $container->registerExtension(new ExtensionA());
+        $container->loadFromExtension('a');
+        $container->registerExtension($b = new ExtensionB());
+        $container->loadFromExtension('b');
+
+        $pass = new MergeExtensionConfigurationPass();
+        $pass->process($container);
+
+        $this->assertSame('user_value', $container->getParameter('key'));
+        $this->assertSame('user_value', $b->parameterKey);
+    }
+}
+
+abstract class Extension implements ExtensionInterface
+{
+    public function getNamespace()
+    {
+        return 'http://example.org/schema/dic/'.$this->getAlias();
+    }
+
+    public function getXsdValidationBasePath()
+    {
+        return false;
+    }
+}
+
+class ExtensionA extends Extension
+{
+    public function load(array $config, ContainerBuilder $container)
+    {
+        $container->getParameterBag()->set('key', 'default_value');
+    }
+
+    public function getAlias()
+    {
+        return 'a';
+    }
+}
+
+class ExtensionB extends Extension
+{
+    public $parameterKey;
+
+    public function load(array $config, ContainerBuilder $container)
+    {
+        $this->parameterKey = $container->getParameter('key');
+    }
+
+    public function getAlias()
+    {
+        return 'b';
+    }
+}