diff --git a/lib/Db/AclMapper.php b/lib/Db/AclMapper.php
index d95f88c46..fd673f678 100644
--- a/lib/Db/AclMapper.php
+++ b/lib/Db/AclMapper.php
@@ -63,13 +63,13 @@ class AclMapper extends DeckMapper implements IPermissionMapper {
 	 */
 	public function isOwner($userId, $aclId): bool {
 		$qb = $this->db->getQueryBuilder();
-		$qb->select('*')
+		$qb->select('acl.id')
 			->from($this->getTableName(), 'acl')
 			->innerJoin('acl', 'deck_boards','b', 'acl.board_id = b.id')
 			->where($qb->expr()->eq('owner', $qb->createNamedParameter($userId, IQueryBuilder::PARAM_STR)))
 			->andWhere($qb->expr()->eq('acl.id', $qb->createNamedParameter($aclId, IQueryBuilder::PARAM_INT)));
 
-		return $qb->executeQuery()->rowCount() > 0;
+		return count($qb->executeQuery()->fetchAll()) > 0;
 	}
 
 	/**
diff --git a/lib/Db/LabelMapper.php b/lib/Db/LabelMapper.php
index be1b68c23..d65b65fd2 100644
--- a/lib/Db/LabelMapper.php
+++ b/lib/Db/LabelMapper.php
@@ -180,13 +180,13 @@ class LabelMapper extends DeckMapper implements IPermissionMapper {
 	 */
 	public function isOwner($userId, $labelId): bool {
 		$qb = $this->db->getQueryBuilder();
-		$qb->select('*')
+		$qb->select('l.id')
 			->from($this->getTableName(), 'l')
 			->innerJoin('l', 'deck_boards' , 'b', 'l.board_id = b.id')
 			->where($qb->expr()->eq('l.id', $qb->createNamedParameter($labelId, IQueryBuilder::PARAM_INT)))
 			->andWhere($qb->expr()->eq('b.owner', $qb->createNamedParameter($userId, IQueryBuilder::PARAM_STR)));
 
-		return $qb->executeQuery()->rowCount() > 0;
+        return count($qb->executeQuery()->fetchAll()) > 0;
 	}
 
 	/**
diff --git a/lib/Db/StackMapper.php b/lib/Db/StackMapper.php
index 9b719d989..9990ad6c5 100644
--- a/lib/Db/StackMapper.php
+++ b/lib/Db/StackMapper.php
@@ -131,13 +131,13 @@ class StackMapper extends DeckMapper implements IPermissionMapper {
 	 */
 	public function isOwner($userId, $stackId): bool {
 		$qb = $this->db->getQueryBuilder();
-		$qb->select('*')
+		$qb->select('s.id')
 			->from($this->getTableName(), 's')
 			->innerJoin('s', 'deck_boards', 'b', 'b.id = s.board_id')
 			->where($qb->expr()->eq('s.id', $qb->createNamedParameter($stackId, IQueryBuilder::PARAM_INT)))
 			->andWhere($qb->expr()->eq('owner', $qb->createNamedParameter($userId, IQueryBuilder::PARAM_STR)));
 
-		return $qb->executeQuery()->rowCount() > 0;
+        return count($qb->executeQuery()->fetchAll()) > 0;
 	}
 
 	/**