diff --git a/apps/dav/lib/CalDAV/CalendarRoot.php b/apps/dav/lib/CalDAV/CalendarRoot.php
index e08264b8f5961..ac5a222cc381d 100644
--- a/apps/dav/lib/CalDAV/CalendarRoot.php
+++ b/apps/dav/lib/CalDAV/CalendarRoot.php
@@ -34,7 +34,7 @@ class CalendarRoot extends \Sabre\CalDAV\CalendarRoot {
 	/** @var LoggerInterface */
 	private $logger;
 
-	public function __construct(PrincipalBackend\BackendInterface $principalBackend, Backend\BackendInterface $caldavBackend, $principalPrefix = 'principals', LoggerInterface $logger) {
+	public function __construct(PrincipalBackend\BackendInterface $principalBackend, Backend\BackendInterface $caldavBackend, $principalPrefix, LoggerInterface $logger) {
 		parent::__construct($principalBackend, $caldavBackend, $principalPrefix);
 		$this->logger = $logger;
 	}