diff --git a/apps/files_sharing/lib/Notification/Notifier.php b/apps/files_sharing/lib/Notification/Notifier.php
index d35e22c935d..58f2a60fcdd 100644
--- a/apps/files_sharing/lib/Notification/Notifier.php
+++ b/apps/files_sharing/lib/Notification/Notifier.php
@@ -157,6 +157,8 @@ class Notifier implements INotifier {
 			if ($share->getStatus() !== IShare::STATUS_PENDING) {
 				throw new AlreadyProcessedException();
 			}
+		} else {
+			throw new \InvalidArgumentException('Invalid share type');
 		}
 
 		switch ($notification->getSubject()) {