diff --git a/biscuit/apps/chronos/model_extensions.py b/biscuit/apps/chronos/model_extensions.py
index 35afb5c3ee89649d941f8a7a8fa96ac7b2c8ba66..25acbd54c8906fcf461662d7c5344082b9f96a8e 100644
--- a/biscuit/apps/chronos/model_extensions.py
+++ b/biscuit/apps/chronos/model_extensions.py
@@ -5,4 +5,4 @@ from .models import Lesson
 
 @Person.property
 def lessons_as_participant(self):
-    return Lesson.objects.filter(groups__member=self)
+    return Lesson.objects.filter(groups__members=self)