diff --git a/src/Symfony/Component/Config/Resource/ClassExistenceResource.php b/src/Symfony/Component/Config/Resource/ClassExistenceResource.php
index 9f904a881e..a692981e19 100644
--- a/src/Symfony/Component/Config/Resource/ClassExistenceResource.php
+++ b/src/Symfony/Component/Config/Resource/ClassExistenceResource.php
@@ -118,8 +118,10 @@ class ClassExistenceResource implements SelfCheckingResourceInterface, \Serializ
 
     /**
      * @throws \ReflectionException When $class is not found and is required
+     *
+     * @internal
      */
-    private static function throwOnRequiredClass($class)
+    public static function throwOnRequiredClass($class)
     {
         if (self::$autoloadedClass === $class) {
             return;