diff --git a/confirmation/migrations/0001_initial.py b/confirmation/migrations/0001_initial.py
index 007b3cba47..3298e64440 100644
--- a/confirmation/migrations/0001_initial.py
+++ b/confirmation/migrations/0001_initial.py
@@ -2,6 +2,7 @@
 from __future__ import unicode_literals
 
 from django.db import models, migrations
+import django.db.models.deletion
 
 
 class Migration(migrations.Migration):
@@ -18,7 +19,7 @@ class Migration(migrations.Migration):
                 ('object_id', models.PositiveIntegerField()),
                 ('date_sent', models.DateTimeField(verbose_name='sent')),
                 ('confirmation_key', models.CharField(max_length=40, verbose_name='activation key')),
-                ('content_type', models.ForeignKey(to='contenttypes.ContentType')),
+                ('content_type', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='contenttypes.ContentType')),
             ],
             options={
                 'verbose_name': 'confirmation email',