diff --git a/aleksis/apps/chronos/models.py b/aleksis/apps/chronos/models.py
index eb5f9c83896c8987436e8cb2c1cfbb95438ff412..f3e7331693b057df03290ebbfd74bfca923e11f8 100644
--- a/aleksis/apps/chronos/models.py
+++ b/aleksis/apps/chronos/models.py
@@ -7,6 +7,7 @@ from datetime import date
 from typing import Any
 
 from django.contrib.contenttypes.models import ContentType
+from django.core.exceptions import PermissionDenied
 from django.core.validators import MinValueValidator
 from django.db import models
 from django.db.models import Q, QuerySet
diff --git a/aleksis/apps/chronos/util/chronos_helpers.py b/aleksis/apps/chronos/util/chronos_helpers.py
index fd5fd6a03debf8cc951828435f14906dcc47989b..70688e8e585200a6709be110d9770d64f33e971d 100644
--- a/aleksis/apps/chronos/util/chronos_helpers.py
+++ b/aleksis/apps/chronos/util/chronos_helpers.py
@@ -2,7 +2,7 @@ from datetime import date, datetime, timedelta
 from typing import TYPE_CHECKING, Optional
 
 from django.db.models import Count, Q
-from django.http import HttpRequest
+from django.http import HttpRequest, HttpResponseNotFound
 from django.shortcuts import get_object_or_404
 
 from guardian.shortcuts import get_objects_for_user