diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
index 6898ea8252..84135b6598 100644
--- a/src/Symfony/Component/HttpKernel/Kernel.php
+++ b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -101,7 +101,9 @@ abstract class Kernel implements KernelInterface, TerminableInterface
         if ($this->debug) {
             error_reporting(-1);
 
-            DebugClassLoader::enable();
+            if (class_exists('Symfony\Component\ClassLoader\DebugClassLoader')) {
+                DebugClassLoader::enable();
+            }
             ErrorHandler::register($this->errorReportingLevel);
             if ('cli' !== php_sapi_name()) {
                 ExceptionHandler::register();