diff --git a/src/Symfony/Component/DependencyInjection/Dumper/Preloader.php b/src/Symfony/Component/DependencyInjection/Dumper/Preloader.php
index 7d4c42c46c..c2c805861b 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/Preloader.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/Preloader.php
@@ -27,7 +27,7 @@ final class Preloader
 
         foreach ($list as $item) {
             if (0 === strpos($item, $cacheDir)) {
-                file_put_contents($file, sprintf("require __DIR__.%s;\n", var_export(substr($item, \strlen($cacheDir)), true)), FILE_APPEND);
+                file_put_contents($file, sprintf("require_once __DIR__.%s;\n", var_export(substr($item, \strlen($cacheDir)), true)), FILE_APPEND);
                 continue;
             }