diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index f0d332adab5ff..e63dcb4ecda54 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -2861,7 +2861,7 @@ public function getDenormalizedData($calendarData) {
 			'size' => strlen($calendarData),
 			'componentType' => $componentType,
 			'firstOccurence' => is_null($firstOccurrence) ? null : max(0, $firstOccurrence),
-			'lastOccurence' => $lastOccurrence,
+			'lastOccurence' => is_null($lastOccurrence) ? null : max(0, $lastOccurrence),
 			'uid' => $uid,
 			'classification' => $classification
 		];