diff --git a/core/lib/Drupal/Core/Config/ConfigEvents.php b/core/lib/Drupal/Core/Config/ConfigEvents.php
index dd4c17f..839b189 100644
--- a/core/lib/Drupal/Core/Config/ConfigEvents.php
+++ b/core/lib/Drupal/Core/Config/ConfigEvents.php
@@ -10,7 +10,7 @@
 /**
  * Defines events for the configuration system.
  */
-class ConfigEvents {
+final class ConfigEvents {
 
   /**
    * Name of event fired when saving the configuration object.