diff --git a/aleksis/apps/alsijil/util/predicates.py b/aleksis/apps/alsijil/util/predicates.py
index 0459a96b8c820c6c439b59349cc065745b84d4f9..d984fafc043be23dfebb13692209a50a4883d690 100644
--- a/aleksis/apps/alsijil/util/predicates.py
+++ b/aleksis/apps/alsijil/util/predicates.py
@@ -312,7 +312,7 @@ def is_lesson_event_teacher(user: User, obj: LessonEvent):
     or a teacher of the course, if the lesson event has one.
     """
     if obj:
-        return obj.course and is_course_teacher(user, obj) or user.person in obj.all_teachers()
+        return obj.course and is_course_teacher(user, obj) or user.person in obj.all_teachers
     return False