diff --git a/aleksis/apps/chronos/models.py b/aleksis/apps/chronos/models.py
index 3940894ee91f84dea9e1fce01987806ffa6cb815..ed6905004d257c6e89bcf22ef0b87cd1a1a248e5 100644
--- a/aleksis/apps/chronos/models.py
+++ b/aleksis/apps/chronos/models.py
@@ -265,7 +265,6 @@ class TimePeriod(ValidityRangeRelatedExtensibleModel):
     @classproperty
     @cache_memoize(3600)
     def period_min(cls) -> int:
-
         return (
             cls.objects.for_current_or_all()
             .aggregate(period__min=Coalesce(Min("period"), 1))
@@ -1080,7 +1079,6 @@ class Event(SchoolTermRelatedExtensibleModel, GroupPropertiesMixin, TeacherPrope
             return _("Event {pk}").format(pk=self.pk)
 
     def get_period_min(self, day) -> int:
-
         return (
             TimePeriod.objects.on_day(day)
             .aggregate(period__min=Coalesce(Min("period"), 1))
diff --git a/aleksis/apps/chronos/tests/test_notifications.py b/aleksis/apps/chronos/tests/test_notifications.py
index 6c8325b972801fd526d3242c7e2564034f625438..9180bc22f997093bd24d594083efc2b0c10969af 100644
--- a/aleksis/apps/chronos/tests/test_notifications.py
+++ b/aleksis/apps/chronos/tests/test_notifications.py
@@ -156,7 +156,6 @@ class NotificationTests(TransactionTestCase):
             TimetableDataChangeTracker()
 
     def test_create_detection(self):
-
         with transaction.atomic():
             tracker = TimetableDataChangeTracker()
 
@@ -187,7 +186,6 @@ class NotificationTests(TransactionTestCase):
             assert change.changed_fields
 
     def test_change_detection(self):
-
         with transaction.atomic():
             lesson_substitution = LessonSubstitution.objects.create(
                 week=20, year=2020, lesson_period=self.period_1, cancelled=True
diff --git a/aleksis/apps/chronos/util/build.py b/aleksis/apps/chronos/util/build.py
index 9379abf55878257dcd4c16fc5d63165561a4aa04..a6c89a347ffdf2cc10e01b705fcad746eb7535e2 100644
--- a/aleksis/apps/chronos/util/build.py
+++ b/aleksis/apps/chronos/util/build.py
@@ -491,7 +491,6 @@ def build_weekdays(
 
     weekdays = []
     for key, name in base[TimePeriod.weekday_min : TimePeriod.weekday_max + 1]:
-
         weekday = {
             "key": key,
             "name": name,