diff --git a/src/Symfony/Framework/ClassCollectionLoader.php b/src/Symfony/Framework/ClassCollectionLoader.php
index d4d36a1298b6..f6a3808fe06a 100644
--- a/src/Symfony/Framework/ClassCollectionLoader.php
+++ b/src/Symfony/Framework/ClassCollectionLoader.php
@@ -18,11 +18,20 @@
  */
 class ClassCollectionLoader
 {
+    static protected $loaded;
+
     /**
      * @throws \InvalidArgumentException When class can't be loaded
      */
     static public function load($classes, $cacheDir, $name, $autoReload)
     {
+        // each $name can only be loaded once per PHP process
+        if (isset(self::$loaded[$name])) {
+            return;
+        }
+
+        self::$loaded[$name] = true;
+
         $classes = array_unique($classes);
 
         $cache = $cacheDir.'/'.$name.'.php';
diff --git a/src/Symfony/Framework/Kernel.php b/src/Symfony/Framework/Kernel.php
index 406cfe44dc59..0298db8362d7 100644
--- a/src/Symfony/Framework/Kernel.php
+++ b/src/Symfony/Framework/Kernel.php
@@ -36,8 +36,6 @@
  */
 abstract class Kernel implements HttpKernelInterface, \Serializable
 {
-    static protected $loaded;
-
     protected $bundles;
     protected $bundleDirs;
     protected $container;
@@ -127,17 +125,12 @@ public function boot()
         $this->container = $this->initializeContainer();
 
         // load core classes
-        // can only be loaded once (for all Kernel in the same process)
-        if (!self::$loaded) {
-            self::$loaded = true;
-
-            ClassCollectionLoader::load(
-                $this->container->getParameter('kernel.compiled_classes'),
-                $this->container->getParameter('kernel.cache_dir'),
-                'classes',
-                $this->container->getParameter('kernel.debug')
-            );
-        }
+        ClassCollectionLoader::load(
+            $this->container->getParameter('kernel.compiled_classes'),
+            $this->container->getParameter('kernel.cache_dir'),
+            'classes',
+            $this->container->getParameter('kernel.debug')
+        );
 
         foreach ($this->bundles as $bundle) {
             $bundle->setContainer($this->container);