diff --git a/aleksis/apps/chronos/migrations/0003_school_term_validity_fixes.py b/aleksis/apps/chronos/migrations/0003_school_term_validity_fixes.py
index 04d0777508fac4500c60a84496567b52cd3e2cec..21237988c6a384ac9af6d3c0dfedd40aedd1d4c8 100644
--- a/aleksis/apps/chronos/migrations/0003_school_term_validity_fixes.py
+++ b/aleksis/apps/chronos/migrations/0003_school_term_validity_fixes.py
@@ -1,27 +1,30 @@
 # Generated by Django 3.0.7 on 2020-06-30 10:46
 
-from django.db import migrations, models
 import django.db.models.deletion
+from django.db import migrations, models
 
 
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('chronos', '0002_school_term_validity'),
+        ("chronos", "0002_school_term_validity"),
     ]
 
     operations = [
-        migrations.RemoveField(
-            model_name='break',
-            name='school_term',
-        ),
+        migrations.RemoveField(model_name="break", name="school_term",),
         migrations.AddField(
-            model_name='break',
-            name='validity',
-            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='+', to='chronos.ValidityRange', verbose_name='Linked validity range'),
+            model_name="break",
+            name="validity",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="+",
+                to="chronos.ValidityRange",
+                verbose_name="Linked validity range",
+            ),
         ),
         migrations.AlterUniqueTogether(
-            name='timeperiod',
-            unique_together={('weekday', 'period', 'validity')},
+            name="timeperiod", unique_together={("weekday", "period", "validity")},
         ),
     ]
diff --git a/aleksis/apps/chronos/preferences.py b/aleksis/apps/chronos/preferences.py
index 4230ceaa88797ebaf32704b695dd2553b8a816e2..6fb45857a27a1907727245f1f4aacad322985674 100644
--- a/aleksis/apps/chronos/preferences.py
+++ b/aleksis/apps/chronos/preferences.py
@@ -3,10 +3,7 @@ from django.utils.translation import gettext as _
 from dynamic_preferences.preferences import Section
 from dynamic_preferences.types import BooleanPreference, IntegerPreference
 
-from aleksis.core.registries import (
-    person_preferences_registry,
-    site_preferences_registry,
-)
+from aleksis.core.registries import person_preferences_registry, site_preferences_registry
 
 chronos = Section("chronos", verbose_name=_("Chronos"))
 
diff --git a/aleksis/apps/chronos/templatetags/week_helpers.py b/aleksis/apps/chronos/templatetags/week_helpers.py
index 727afdf7bf99d28363f84cdba08f21233974df18..c97703175ec5c4f39cf1757b5ee426bddb4e0dbb 100644
--- a/aleksis/apps/chronos/templatetags/week_helpers.py
+++ b/aleksis/apps/chronos/templatetags/week_helpers.py
@@ -4,11 +4,7 @@ from typing import Optional, Union
 from django import template
 from django.db.models.query import QuerySet
 
-from aleksis.apps.chronos.util.date import (
-    CalendarWeek,
-    week_period_to_date,
-    week_weekday_to_date,
-)
+from aleksis.apps.chronos.util.date import CalendarWeek, week_period_to_date, week_weekday_to_date
 
 register = template.Library()