diff --git a/lib/Db/ReaderMapper.php b/lib/Db/ReaderMapper.php
index 1f6af8d..ce6b9be 100644
--- a/lib/Db/ReaderMapper.php
+++ b/lib/Db/ReaderMapper.php
@@ -25,10 +25,10 @@ abstract class ReaderMapper extends QBMapper {
 	/**
 	 * @param IDBConnection $db Instance of the Db abstraction layer
 	 * @param string $table the name of the table. set this to allow entity
-	 * @param class-string<ReaderEntity>|null $entity the name of the entity that the sql should be mapped to queries without using sql
+	 * @param class-string<ReaderEntity> $entity the name of the entity that the sql should be mapped to queries without using sql
 	 * @param Time $time
 	 */
-	public function __construct(IDBConnection $db, string $table, ?string $entity = null, Time $time) {
+	public function __construct(IDBConnection $db, string $table, string $entity, Time $time) {
 		parent::__construct($db, $table, $entity);
 		$this->time = $time;
 	}
diff --git a/lib/Hooks.php b/lib/Hooks.php
index 35cea44..3864fb3 100644
--- a/lib/Hooks.php
+++ b/lib/Hooks.php
@@ -39,7 +39,7 @@ class Hooks {
 		}
 	}
 
-	protected function deleteFile(IDBConnection $connection, int $fileId): void {
+	protected static function deleteFile(IDBConnection $connection, int $fileId): void {
 		$queryBuilder = $connection->getQueryBuilder();
 		$queryBuilder->delete('reader_bookmarks')->where('file_id = file_id')->setParameter('file_id', $fileId);
 		$queryBuilder->executeStatement();
@@ -49,7 +49,7 @@ class Hooks {
 		$queryBuilder->executeStatement();
 	}
 
-	protected function deleteUser(IDBConnection $connection, string $userId): void {
+	protected static function deleteUser(IDBConnection $connection, string $userId): void {
 		$queryBuilder = $connection->getQueryBuilder();
 		$queryBuilder->delete('reader_bookmarks')->where('user_id = user_id')->setParameter('user_id', $userId);
 		$queryBuilder->executeStatement();