diff --git a/lib/DAV/CalendarPlugin.php b/lib/DAV/CalendarPlugin.php
index e7c9ab6b20..1ce8447fbc 100644
--- a/lib/DAV/CalendarPlugin.php
+++ b/lib/DAV/CalendarPlugin.php
@@ -15,6 +15,8 @@
 
 class CalendarPlugin implements ICalendarProvider {
 
+	private const USER_PRINCIPAL_PREFIX = 'principals/users/';
+
 	/** @var DeckCalendarBackend */
 	private $backend;
 	/** @var ConfigService */
@@ -33,7 +35,7 @@ public function getAppId(): string {
 	}
 
 	public function fetchAllForCalendarHome(string $principalUri): array {
-		if (!$this->calendarIntegrationEnabled) {
+		if (!$this->calendarIntegrationEnabled || !$this->isOwnCalendarHome($principalUri)) {
 			return [];
 		}
 
@@ -46,7 +48,7 @@ public function fetchAllForCalendarHome(string $principalUri): array {
 	}
 
 	public function hasCalendarInCalendarHome(string $principalUri, string $calendarUri): bool {
-		if (!$this->calendarIntegrationEnabled) {
+		if (!$this->calendarIntegrationEnabled || !$this->isOwnCalendarHome($principalUri)) {
 			return false;
 		}
 
@@ -71,4 +73,10 @@ public function getCalendarInCalendarHome(string $principalUri, string $calendar
 		}
 		return null;
 	}
+
+	private function isOwnCalendarHome(string $principalUri): bool {
+		$userId = $this->configService->getUserId();
+
+		return $userId !== null && $principalUri === self::USER_PRINCIPAL_PREFIX . $userId;
+	}
 }