diff --git a/lib/Tools/Db/ExtendedQueryBuilder.php b/lib/Tools/Db/ExtendedQueryBuilder.php
index 5af9fff10..d6d4b9ba3 100644
--- a/lib/Tools/Db/ExtendedQueryBuilder.php
+++ b/lib/Tools/Db/ExtendedQueryBuilder.php
@@ -911,7 +911,7 @@ public function exprFilterInArray(string $field, array $values, string $alias =
 	 *
 	 * @return string
 	 */
-	public function exprFilterBitwise(string $field, int $flag, string $alias = ''): string {
+	public function exprFilterBitwise(string $field, int $flag, string $alias = ''): IQueryFunction {
 		if ($this->getType() === DBALQueryBuilder::SELECT) {
 			$field = (($alias === '') ? $this->getDefaultSelectAlias() : $alias) . '.' . $field;
 		}