diff --git a/core/lib/Drupal/Core/KeyValueStore/FileStorage.php b/core/lib/Drupal/Core/KeyValueStore/FileStorage.php
index 12f831b..8b7ba40 100644
--- a/core/lib/Drupal/Core/KeyValueStore/FileStorage.php
+++ b/core/lib/Drupal/Core/KeyValueStore/FileStorage.php
@@ -72,7 +72,9 @@ public function getAll() {
    * {@inheritdoc}
    */
   public function set($key, $value) {
-    file_put_contents($this->path . "/$key.php", '<?php $value = ' . var_export($value, TRUE) . ';');
+    $content = '<?php $value = ' . var_export($value, TRUE) . ';';
+    $content = strtr($content, array('stdClass::__set_state' => '(object)'));
+    file_put_contents($this->path . "/$key.php", $content);
   }
 
   /**