diff --git a/aleksis/apps/chronos/migrations/0006_extended_data.py b/aleksis/apps/chronos/migrations/0006_extended_data.py
new file mode 100644
index 0000000000000000000000000000000000000000..7555ef89e9d478baf320d50049c7f71b4d389a48
--- /dev/null
+++ b/aleksis/apps/chronos/migrations/0006_extended_data.py
@@ -0,0 +1,24 @@
+# Generated by Django 3.0.2 on 2020-01-19 13:15
+
+import django.contrib.postgres.fields.jsonb
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('chronos', '0005_remove_school_related'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='lessonperiod',
+            name='extended_data',
+            field=django.contrib.postgres.fields.jsonb.JSONField(default=dict, editable=False),
+        ),
+        migrations.AlterField(
+            model_name='timeperiod',
+            name='weekday',
+            field=models.PositiveSmallIntegerField(choices=[(0, 'Montag'), (1, 'Dienstag'), (2, 'Mittwoch'), (3, 'Donnerstag'), (4, 'Freitag'), (5, 'Samstag'), (6, 'Sonntag')], verbose_name='Week day'),
+        ),
+    ]
diff --git a/aleksis/apps/chronos/models.py b/aleksis/apps/chronos/models.py
index bc78546e95db17f5bd9e301a9597344e1285dad9..895420f186127b31c2f4527478a9bbe3f5c176b2 100644
--- a/aleksis/apps/chronos/models.py
+++ b/aleksis/apps/chronos/models.py
@@ -368,7 +368,7 @@ class LessonSubstitution(models.Model):
         ]
 
 
-class LessonPeriod(models.Model, ExtensibleModel):
+class LessonPeriod(ExtensibleModel):
     objects = LessonPeriodManager.from_queryset(LessonPeriodQuerySet)()
 
     lesson = models.ForeignKey("Lesson", models.CASCADE, related_name="lesson_periods")