diff --git a/core/lib/Drupal/Core/Block/BlockBase.php b/core/lib/Drupal/Core/Block/BlockBase.php
index d06960d..3e33e14 100644
--- a/core/lib/Drupal/Core/Block/BlockBase.php
+++ b/core/lib/Drupal/Core/Block/BlockBase.php
@@ -281,7 +281,7 @@ public function getFormClass($operation) {
       return $this->getPluginDefinition()['forms'][$operation];
     }
     elseif ($operation == 'configure' && $this instanceof PluginFormInterface) {
-      return static::CLASS;
+      return static::class;
     }
   }