diff --git a/heltour/tournament/migrations/0021_auto_20160724_1855.py b/heltour/tournament/migrations/0021_auto_20160724_1855.py
index d9c66f4d..01b84221 100644
--- a/heltour/tournament/migrations/0021_auto_20160724_1855.py
+++ b/heltour/tournament/migrations/0021_auto_20160724_1855.py
@@ -20,7 +20,7 @@ class Migration(migrations.Migration):
         migrations.AlterField(
             model_name='registration',
             name='already_in_slack_group',
-            field=models.BooleanField(),
+            field=models.BooleanField(default=False),
         ),
         migrations.AlterField(
             model_name='registration',