diff --git a/lib/GroupHelper.php b/lib/GroupHelper.php
index 5b8a81a63..c9766a4ad 100644
--- a/lib/GroupHelper.php
+++ b/lib/GroupHelper.php
@@ -150,8 +150,8 @@ protected function arrayToEvent(array $row) {
 			->setAffectedUser((string) $row['affecteduser'])
 			->setAuthor((string) $row['user'])
 			->setTimestamp((int) $row['timestamp'])
-			->setSubject((string) $row['subject'], json_decode($row['subjectparams'], true))
-			->setMessage((string) $row['message'], json_decode($row['messageparams'], true))
+			->setSubject((string) $row['subject'], (array) json_decode($row['subjectparams'], true))
+			->setMessage((string) $row['message'], (array) json_decode($row['messageparams'], true))
 			->setObject((string) $row['object_type'], (int) $row['object_id'], (string) $row['file'])
 			->setLink((string) $row['link']);