diff --git a/aleksis/apps/chronos/model_extensions.py b/aleksis/apps/chronos/model_extensions.py
index c68d37260c2815ddf259feb7137fc9bb97122a29..8f16b828ae522f64daa3df7371871c8afcc4a0c3 100644
--- a/aleksis/apps/chronos/model_extensions.py
+++ b/aleksis/apps/chronos/model_extensions.py
@@ -7,7 +7,7 @@ from .models import Lesson, LessonPeriod
 def is_teacher(self):
     """ Check if the user has lessons as a teacher """
 
-    return Lesson.objects.filter(teachers=self).exists()
+    return self.lesson_periods_as_teacher.exists()
 
 
 @Person.property