diff --git a/src/GraphQl/Error/ErrorHandler.php b/src/GraphQl/Error/ErrorHandler.php
index 778c42e1ae8..955445cd982 100644
--- a/src/GraphQl/Error/ErrorHandler.php
+++ b/src/GraphQl/Error/ErrorHandler.php
@@ -20,7 +20,7 @@
  *
  * @author Ollie Harridge <code@oll.ie>
  */
-class ErrorHandler implements ErrorHandlerInterface
+final class ErrorHandler implements ErrorHandlerInterface
 {
     /**
      * {@inheritdoc}