1 files changed, 2 insertions, 0 deletions
diff --git a/models.py b/models.py
index 56c1845..5de1df2 100644
--- a/models.py
+++ b/models.py
@@ -179,6 +179,8 @@ class CourseManager(Manager):
                    .prefetch_related("rooms")
         elif isinstance(obj, Room):
             qs = qs.filter(rooms__in=(obj,), **criteria)
+        else:
+            raise(TypeError, "obj must be a Group or a Room")
 
         return qs.order_by("begin")