diff --git a/lib/Db/CardMapper.php b/lib/Db/CardMapper.php
index 7bcf65741..8866137a0 100644
--- a/lib/Db/CardMapper.php
+++ b/lib/Db/CardMapper.php
@@ -243,7 +243,7 @@ class CardMapper extends QBMapper implements IPermissionMapper {
 		$qb->select('id','title','duedate','notified')
 			->from('deck_cards')
 			->where($qb->expr()->lt('duedate', $qb->createFunction('NOW()')))
-			->andWhere($qb->expr()->eq('notified', $qb->createNamedParameter(false)))
+			->andWhere($qb->expr()->eq('notified', $qb->createNamedParameter(false, IQueryBuilder::PARAM_BOOL)))
 			->andWhere($qb->expr()->eq('archived', $qb->createNamedParameter(false, IQueryBuilder::PARAM_BOOL)))
 			->andWhere($qb->expr()->eq('deleted_at', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT)));
 		return $this->findEntities($qb);