diff --git a/apps/dav/lib/caldav/birthdayservice.php b/apps/dav/lib/caldav/birthdayservice.php
index 624c208694..5a0dfb6992 100644
--- a/apps/dav/lib/caldav/birthdayservice.php
+++ b/apps/dav/lib/caldav/birthdayservice.php
@@ -140,16 +140,10 @@ class BirthdayService {
 			$date
 		);
 		$vEvent->DTEND['VALUE'] = 'DATE';
-//		$lm = new \DateTime('@' . $this->lastModified());
-//		$lm->setTimeZone(new \DateTimeZone('UTC'));
-//		$vEvent->DTSTAMP->setDateTime($lm);
 		$vEvent->{'UID'} = $doc->UID;
 		$vEvent->{'RRULE'} = 'FREQ=YEARLY';
 		$vEvent->{'SUMMARY'} = $title . ' (' . $date->format('Y') . ')';
 		$vEvent->{'TRANSP'} = 'TRANSPARENT';
-//		$appInfo = \OCP\App::getAppInfo('contacts');
-//		$appVersion = \OCP\App::getAppVersion('contacts');
-//		$vCal->PRODID = '-//ownCloud//NONSGML ' . $appInfo['name'] . ' ' . $appVersion . '//EN';
 		$vCal->add($vEvent);
 		return $vCal;
 	}
diff --git a/apps/dav/lib/caldav/calendar.php b/apps/dav/lib/caldav/calendar.php
index 8ed5b6563d..6b34d570eb 100644
--- a/apps/dav/lib/caldav/calendar.php
+++ b/apps/dav/lib/caldav/calendar.php
@@ -80,6 +80,10 @@ class Calendar extends \Sabre\CalDAV\Calendar implements IShareable {
 	}
 
 	function delete() {
+		if ($this->getName() === BirthdayService::BIRTHDAY_CALENDAR_URI) {
+			throw new Forbidden();
+		}
+
 		if (isset($this->calendarInfo['{http://owncloud.org/ns}owner-principal'])) {
 			$principal = 'principal:' . parent::getOwner();
 			$shares = $this->getShares();
diff --git a/apps/dav/tests/unit/caldav/calendartest.php b/apps/dav/tests/unit/caldav/calendartest.php
index 93b3f4bff8..4a3c94e8ab 100644
--- a/apps/dav/tests/unit/caldav/calendartest.php
+++ b/apps/dav/tests/unit/caldav/calendartest.php
@@ -37,7 +37,8 @@ class CalendarTest extends TestCase {
 		$calendarInfo = [
 			'{http://owncloud.org/ns}owner-principal' => 'user1',
 			'principaluri' => 'user2',
-			'id' => 666
+			'id' => 666,
+			'uri' => 'cal',
 		];
 		$c = new Calendar($backend, $calendarInfo);
 		$c->delete();
@@ -56,7 +57,8 @@ class CalendarTest extends TestCase {
 		$calendarInfo = [
 			'{http://owncloud.org/ns}owner-principal' => 'user1',
 			'principaluri' => 'user2',
-			'id' => 666
+			'id' => 666,
+			'uri' => 'cal',
 		];
 		$c = new Calendar($backend, $calendarInfo);
 		$c->delete();