diff --git a/aleksis/apps/chronos/managers.py b/aleksis/apps/chronos/managers.py
index 3d8f8e0ac263587b789d845ca3403510c30467d9..ce1670f53f79bd21e71b59eb260603825edf0f57 100644
--- a/aleksis/apps/chronos/managers.py
+++ b/aleksis/apps/chronos/managers.py
@@ -878,12 +878,10 @@ class LessonEventQuerySet(PolymorphicQuerySet):
 
     def for_participant(self, person: Union[int, Person]) -> "LessonEventQuerySet":
         """Get all lesson events the person participates in (including amends)."""
-        amended = self.filter(
-            Q(amended_by__isnull=False) | Q(groups__members=person)
-        ).values_list("amended_by__pk", flat=True)
-        return self.filter(
-            Q(groups__members=person) | Q(pk__in=amended)
-        ).distinct()
+        amended = self.filter(Q(amended_by__isnull=False) | Q(groups__members=person)).values_list(
+            "amended_by__pk", flat=True
+        )
+        return self.filter(Q(groups__members=person) | Q(pk__in=amended)).distinct()
 
     def for_group(self, group: Union[int, Group]) -> "LessonEventQuerySet":
         """Get all lesson events for a certain group (including amends/as parent group)."""
diff --git a/aleksis/apps/chronos/preferences.py b/aleksis/apps/chronos/preferences.py
index e75062cc2209c6a2affddbf2f52a45aaebd0f0d2..d26653216f30acefac397ead20f97193546b0f0a 100644
--- a/aleksis/apps/chronos/preferences.py
+++ b/aleksis/apps/chronos/preferences.py
@@ -127,9 +127,6 @@ class GroupTypesTimetables(ModelMultipleChoicePreference):
     verbose_name = _("Group types to show in timetables")
     help_text = _("If you leave it empty, all groups will be shown.")
 
-    def get_queryset(self):
-        return GroupType.objects.managed_and_unmanaged()
-
 
 @site_preferences_registry.register
 class LessonEventFeedColor(StringPreference):