diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php
index caade2d..1c87b05 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php
@@ -24,10 +24,11 @@ class TwigExtensionPass implements CompilerPassInterface {
   public function process(ContainerBuilder $container) {
     $twig_extension_hash = '';
     foreach (array_keys($container->findTaggedServiceIds('twig.extension')) as $service_id) {
-      $reflecton = new \ReflectionClass($container->getDefinition($service_id)->getClass());
-      // We use mtime to invalidate both on new extensions and changes of
-      // existing ones.
-      $twig_extension_hash .= filemtime($reflecton->getFileName());
+      $class_name = $container->getDefinition($service_id)->getClass();
+      $reflecton = new \ReflectionClass($class_name);
+      // We use the class names as hash in order to invalidate on new extensions
+      // and mtime for everytime we change an existing file.
+      $twig_extension_hash .= $class_name . filemtime($reflecton->getFileName());
     }
 
     $container->setParameter('twig_extension_hash', $twig_extension_hash);