diff --git a/lib/Db/CardMapper.php b/lib/Db/CardMapper.php
index b13eb5996..f42d7a339 100644
--- a/lib/Db/CardMapper.php
+++ b/lib/Db/CardMapper.php
@@ -23,21 +23,31 @@
 
 namespace OCA\Deck\Db;
 
-use OC\Notification\Notification;
 use OCP\AppFramework\Db\Entity;
 use OCP\IDBConnection;
 use OCP\IUserManager;
+use OCP\Notification\IManager;
 
 
 class CardMapper extends DeckMapper implements IPermissionMapper {
 
+	/** @var LabelMapper */
 	private $labelMapper;
+	/** @var IUserManager */
 	private $userManager;
+	/** @var Manager */
+	private $notificationManager;
 
-	public function __construct(IDBConnection $db, LabelMapper $labelMapper, IUserManager $userManager) {
+	public function __construct(
+		IDBConnection $db,
+		LabelMapper $labelMapper,
+		IUserManager $userManager,
+		IManager $notificationManager
+	) {
 		parent::__construct($db, 'deck_cards', '\OCA\Deck\Db\Card');
 		$this->labelMapper = $labelMapper;
 		$this->userManager = $userManager;
+		$this->notificationManager = $notificationManager;
 	}
 
 	public function insert(Entity $entity) {
@@ -55,10 +65,13 @@ class CardMapper extends DeckMapper implements IPermissionMapper {
 			$existing = $this->find($entity->getId());
 			if ($existing->getDuedate() !== $entity->getDuedate())
 				$entity->setNotified(false);
+			// remove pending notifications
+			$notification = $this->notificationManager->createNotification();
+			$notification
+				->setApp('deck')
+				->setObject('card', $entity->getId());
+			$this->notificationManager->markProcessed($notification);
 		}
-
-		// TODO: also remove pending notifications
-
 		return parent::update($entity);
 	}
 
@@ -75,6 +88,7 @@ class CardMapper extends DeckMapper implements IPermissionMapper {
 	public function find($id) {
 		$sql = 'SELECT * FROM `*PREFIX*deck_cards` ' .
 			'WHERE `id` = ?';
+		/** @var Card $card */
 		$card = $this->findEntity($sql, [$id]);
 		$labels = $this->labelMapper->findAssignedLabelsForCard($card->id);
 		$card->setLabels($labels);
diff --git a/lib/Notification/NotificationHelper.php b/lib/Notification/NotificationHelper.php
index ea2cb0c72..00157e13a 100644
--- a/lib/Notification/NotificationHelper.php
+++ b/lib/Notification/NotificationHelper.php
@@ -52,11 +52,13 @@ class NotificationHelper {
 		CardMapper $cardMapper,
 		BoardMapper $boardMapper,
 		IManager $notificationManager,
+		IGroupManager $groupManager,
 		$userId
 	) {
 		$this->cardMapper = $cardMapper;
 		$this->boardMapper = $boardMapper;
 		$this->notificationManager = $notificationManager;
+		$this->groupManager = $groupManager;
 		$this->currentUser = $userId;
 	}
 
@@ -100,7 +102,6 @@ class NotificationHelper {
 			$this->notificationManager->notify($notification);
 		}
 		if ($acl->getType() === Acl::PERMISSION_TYPE_GROUP) {
-			$this->groupManager = \OC::$server->getGroupManager();
 			$group = $this->groupManager->get($acl->getParticipant());
 			foreach ($group->getUsers() as $user) {
 				$notification = $this->generateBoardShared($board, $user->getUID());
@@ -139,7 +140,7 @@ class NotificationHelper {
 				$users[] = $acl->getParticipant();
 			}
 			if ($acl->getType() === Acl::PERMISSION_TYPE_GROUP) {
-				$group = \OC::$server->getGroupManager()->get($acl->getParticipant());
+				$group = $this->groupManager->get($acl->getParticipant());
 				/** @var IUser $user */
 				foreach ($group->getUsers() as $user) {
 					$users[] = $user->getUID();