diff --git a/src/Exception/TokenMismatchException.php b/src/Exception/TokenMismatchException.php
index 5d49f37..db103f9 100644
--- a/src/Exception/TokenMismatchException.php
+++ b/src/Exception/TokenMismatchException.php
@@ -9,7 +9,7 @@
 /**
  * Represents an HTTP 412 error caused by a mismatched CSRF token
  */
-class TokenMismatchException extends PreconditionFailedHttpException
+final class TokenMismatchException extends PreconditionFailedHttpException
 {
     /**
      * Constructor