diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index f27fe2512..2b5a7367d 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -10,4 +10,14 @@
  * file that was distributed with this source code.
  */
 
-require __DIR__.'/../vendor/.composer/autoload.php';
+if (file_exists(__DIR__.'/../vendor/.composer/autoload.php')) {
+    require __DIR__.'/../vendor/.composer/autoload.php';
+} else {
+    require __DIR__.'/../src/Composer/Autoload/ClassLoader.php';
+
+    $loader = new Composer\Autoload\ClassLoader();
+    $loader->add('Composer\\', dirname(__DIR__).'/src/');
+    $loader->add('Symfony\\Component\\', dirname(__DIR__).'/src/');
+    $loader->add('Composer_', dirname(__DIR__).'/src/');
+    $loader->register();
+}
\ No newline at end of file