diff --git a/lib/Db/Stack.php b/lib/Db/Stack.php
index c414f52a8..0b9ceb8dc 100644
--- a/lib/Db/Stack.php
+++ b/lib/Db/Stack.php
@@ -25,6 +25,13 @@ namespace OCA\Deck\Db;
 
 use Sabre\VObject\Component\VCalendar;
 
+/**
+ * @method int getId()
+ * @method int getBoardId()
+ * @method int getDeletedAt()
+ * @method int getLastModified()
+ * @method int getOrder()
+ */
 class Stack extends RelationalEntity {
 	protected $title;
 	protected $boardId;
diff --git a/lib/Db/StackMapper.php b/lib/Db/StackMapper.php
index 6f900f45f..f1c77d7d7 100644
--- a/lib/Db/StackMapper.php
+++ b/lib/Db/StackMapper.php
@@ -25,6 +25,7 @@ namespace OCA\Deck\Db;
 
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Db\Entity;
+use OCP\AppFramework\Db\IMapperException;
 use OCP\AppFramework\Db\MultipleObjectsReturnedException;
 use OCP\IDBConnection;
 
@@ -48,6 +49,24 @@ class StackMapper extends DeckMapper implements IPermissionMapper {
 		return $this->findEntity($sql, [$id]);
 	}
 
+	/**
+	 * @param $cardId
+	 * @return Stack|null
+	 */
+	public function findStackFromCardId($cardId): ?Stack {
+		$sql = <<<SQL
+SELECT s.* 
+FROM `*PREFIX*deck_stacks` as `s`
+INNER JOIN `*PREFIX*deck_cards` as `c` ON s.id = c.stack_id
+WHERE c.id = ?
+SQL;
+		try {
+			return $this->findEntity($sql, [$cardId]);
+		} catch (IMapperException $e) {
+			return null;
+		}
+	}
+
 
 	public function findAll($boardId, $limit = null, $offset = null) {
 		$sql = 'SELECT * FROM `*PREFIX*deck_stacks` WHERE `board_id` = ? AND deleted_at = 0 ORDER BY `order`, `id`';
diff --git a/lib/Notification/Notifier.php b/lib/Notification/Notifier.php
index fe2676ef8..dac50bcb2 100644
--- a/lib/Notification/Notifier.php
+++ b/lib/Notification/Notifier.php
@@ -101,15 +101,12 @@ class Notifier implements INotifier {
 		switch ($notification->getSubject()) {
 			case 'card-assigned':
 				$cardId = $notification->getObjectId();
-				$boardId = $this->cardMapper->findBoardId($cardId);
+				$stack = $this->stackMapper->findStackFromCardId($cardId);
+				$boardId = $stack ? $stack->getBoardId() : null;
 				if (!$boardId) {
 					throw new AlreadyProcessedException();
 				}
 
-				$card = $this->cardMapper->find($cardId);
-				$stackId = $card->getStackId();
-				$stack = $this->stackMapper->find($stackId);
-
 				$initiator = $this->userManager->get($params[2]);
 				if ($initiator !== null) {
 					$dn = $initiator->getDisplayName();
@@ -147,15 +144,12 @@ class Notifier implements INotifier {
 				break;
 			case 'card-overdue':
 				$cardId = $notification->getObjectId();
-				$boardId = $this->cardMapper->findBoardId($cardId);
+				$stack = $this->stackMapper->findStackFromCardId($cardId);
+				$boardId = $stack ? $stack->getBoardId() : null;
 				if (!$boardId) {
 					throw new AlreadyProcessedException();
 				}
 
-				$card = $this->cardMapper->find($cardId);
-				$stackId = $card->getStackId();
-				$stack = $this->stackMapper->find($stackId);
-
 				$notification->setParsedSubject(
 					(string) $l->t('The card "%s" on "%s" has reached its due date.', $params)
 				);
@@ -182,15 +176,12 @@ class Notifier implements INotifier {
 				break;
 			case 'card-comment-mentioned':
 				$cardId = $notification->getObjectId();
-				$boardId = $this->cardMapper->findBoardId($cardId);
+				$stack = $this->stackMapper->findStackFromCardId($cardId);
+				$boardId = $stack ? $stack->getBoardId() : null;
 				if (!$boardId) {
 					throw new AlreadyProcessedException();
 				}
 
-				$card = $this->cardMapper->find($cardId);
-				$stackId = $card->getStackId();
-				$stack = $this->stackMapper->find($stackId);
-
 				$initiator = $this->userManager->get($params[2]);
 				if ($initiator !== null) {
 					$dn = $initiator->getDisplayName();