diff --git a/things_for_testing/models.py b/things_for_testing/models.py
index 3edc6c3..8a87571 100644
--- a/things_for_testing/models.py
+++ b/things_for_testing/models.py
@@ -1,5 +1,5 @@
 from django.db import models
-from django_kepi import register_type
+from django_kepi import register_type, TombstoneException
 from django_kepi import models as kepi_models
 
 class ThingUser(models.Model):