diff --git a/core/lib/Drupal/Core/Site/Settings.php b/core/lib/Drupal/Core/Site/Settings.php
index 4fe80b3..01e1fe6 100644
--- a/core/lib/Drupal/Core/Site/Settings.php
+++ b/core/lib/Drupal/Core/Site/Settings.php
@@ -54,6 +54,19 @@ public static function getInstance() {
   }
 
   /**
+   * Protects creating with clone.
+   */
+  private function __clone() {
+  }
+
+  /**
+   * Prevents settings from being serialized.
+   */
+  public function __sleep() {
+    throw new BadMethodCallException('Settings cannot be serialized.');
+  }
+
+  /**
    * Returns a setting.
    *
    * Settings can be set in settings.php in the $settings array and requested