diff --git a/Classes/Domain/Finishers/MjmlEmailFinisher.php b/Classes/Domain/Finishers/MjmlEmailFinisher.php
index aac53e7..656b313 100644
--- a/Classes/Domain/Finishers/MjmlEmailFinisher.php
+++ b/Classes/Domain/Finishers/MjmlEmailFinisher.php
@@ -15,7 +15,7 @@ class MjmlEmailFinisher extends \TYPO3\CMS\Form\Domain\Finishers\EmailFinisher
      * @return StandaloneView
      * @throws FinisherException
      */
-    protected function initializeStandaloneView(FormRuntime $formRuntime, string $format): StandaloneView
+    protected function initializeStandaloneView(FormRuntime $formRuntime, string $format = 'Html'): StandaloneView
     {
         $standaloneView = $this->objectManager->get(MjmlBasedView::class);