diff --git a/pretix_public_registrations/signals.py b/pretix_public_registrations/signals.py
index 561f0d9359c504995359cacc5944bf7b2e69a4ee..940ae471ea982b1adf17beee0641941da11e6493 100644
--- a/pretix_public_registrations/signals.py
+++ b/pretix_public_registrations/signals.py
@@ -8,6 +8,11 @@ from i18nfield.strings import LazyI18nString
 from pretix.presale.signals import question_form_fields, front_page_bottom, process_response, html_head
 from pretix.control.signals import nav_event_settings
 from pretix.base.models import OrderPosition
+from pretix.base.settings import settings_hierarkey
+
+
+settings_hierarkey.add_default('public_registrations_items', None, list)
+settings_hierarkey.add_default('public_registrations_questions', None, list)
 
 
 @receiver(html_head, dispatch_uid="public_registrations_html_head")