diff --git a/chrono/agendas/migrations/0025_auto_20181206_1252.py b/chrono/agendas/migrations/0025_auto_20181206_1252.py
new file mode 100644
index 00000000..637f6973
--- /dev/null
+++ b/chrono/agendas/migrations/0025_auto_20181206_1252.py
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.12 on 2018-12-06 12:52
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('agendas', '0024_auto_20180426_1127'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='agenda',
+            name='edit_role',
+            field=models.ForeignKey(blank=True, default=None, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='+', to='auth.Group', verbose_name='Edit Role'),
+        ),
+        migrations.AlterField(
+            model_name='agenda',
+            name='view_role',
+            field=models.ForeignKey(blank=True, default=None, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='+', to='auth.Group', verbose_name='View Role'),
+        ),
+    ]
diff --git a/chrono/agendas/models.py b/chrono/agendas/models.py
index 7540d21f..92cde042 100644
--- a/chrono/agendas/models.py
+++ b/chrono/agendas/models.py
@@ -66,9 +66,11 @@ class Agenda(models.Model):
     maximal_booking_delay = models.PositiveIntegerField(
             _('Maximal booking delay (in days)'), default=56) # eight weeks
     edit_role = models.ForeignKey(Group, blank=True, null=True, default=None,
-            related_name='+', verbose_name=_('Edit Role'))
+            related_name='+', verbose_name=_('Edit Role'),
+            on_delete=models.SET_NULL)
     view_role = models.ForeignKey(Group, blank=True, null=True, default=None,
-            related_name='+', verbose_name=_('View Role'))
+            related_name='+', verbose_name=_('View Role'),
+            on_delete=models.SET_NULL)
 
     class Meta:
         ordering = ['label']
diff --git a/tests/test_agendas.py b/tests/test_agendas.py
index c0bef223..d2d053d8 100644
--- a/tests/test_agendas.py
+++ b/tests/test_agendas.py
@@ -6,6 +6,7 @@ import requests
 
 
 from django.utils.timezone import now, make_aware, localtime
+from django.contrib.auth.models import Group
 from django.core.management import call_command
 from django.core.management.base import CommandError
 
@@ -454,3 +455,15 @@ def test_timeperiodexception_creation_from_ics_with_recurrences_atreal():
     desk = Desk(label='Test atreal desk', agenda=agenda)
     desk.save()
     assert desk.create_timeperiod_exceptions_from_ics(ICS_ATREAL)
+
+
+def test_management_role_deletion():
+    group = Group(name=u'Group')
+    group.save()
+    agenda = Agenda(label=u'Test agenda', edit_role=group, view_role=group)
+    agenda.save()
+
+    Group.objects.all().delete()
+
+    Agenda.objects.get(id=agenda.id).view_role is None
+    Agenda.objects.get(id=agenda.id).edit_role is None