diff --git a/lib/models/Course.class.php b/lib/models/Course.class.php
index 98f2fecd42f5e47770718136126f7a7555385855..34b7d747645716df78394af54076365e7676fe62 100644
--- a/lib/models/Course.class.php
+++ b/lib/models/Course.class.php
@@ -1096,7 +1096,7 @@ class Course extends SimpleORMap implements Range, PrivacyObject, StudipItem, Fe
     public function isCalendarReadable(?string $user_id = null): bool
     {
         if ($user_id === null) {
-            $user_id = self::findCurrent()->id;
+            $user_id = User::findCurrent()->id;
         }
 
         //Calendar read permissions are granted for all participants