diff --git a/lib/Service/CardService.php b/lib/Service/CardService.php
index cd45ca129..af0eb0103 100644
--- a/lib/Service/CardService.php
+++ b/lib/Service/CardService.php
@@ -337,7 +337,7 @@ class CardService {
 		$card->setType($type);
 		$card->setOrder($order);
 		$card->setOwner($owner);
-		$card->setDuedate(new \DateTime($duedate));
+		$card->setDuedate($duedate ? new \DateTime($duedate) : null);
 		$resetDuedateNotification = false;
 		if (
 			$card->getDuedate() === null ||