diff --git a/aleksis/apps/untis/util/mysql/importers/common_data.py b/aleksis/apps/untis/util/mysql/importers/common_data.py
index e539af7de1e0a42a96a682b102efe391b35c2a8d..12d7a8833c5d7cb1eac838e658f543f171ef6af9 100644
--- a/aleksis/apps/untis/util/mysql/importers/common_data.py
+++ b/aleksis/apps/untis/util/mysql/importers/common_data.py
@@ -416,7 +416,7 @@ def import_time_periods() -> Dict[int, Dict[int, chronos_models.TimePeriod]]:
 
     periods = (
         run_default_filter(mysql_models.Commondata.objects, filter_term=False)
-        .filter(id=CommonDataId.PERIOD)
+        .filter(id=CommonDataId.PERIOD.value)
         .order_by("number", "number1")
     )
 
diff --git a/aleksis/apps/untis/util/mysql/importers/substitutions.py b/aleksis/apps/untis/util/mysql/importers/substitutions.py
index 2f62bf25a2eaa0a5d0c9b7b50229819ccb241b29..33f6214c444735f705498d7731f187f1268c8e62 100644
--- a/aleksis/apps/untis/util/mysql/importers/substitutions.py
+++ b/aleksis/apps/untis/util/mysql/importers/substitutions.py
@@ -65,9 +65,9 @@ def import_substitutions(teachers_ref, subjects_ref, rooms_ref, classes_ref, sup
 
         # Cancellation?
         cancelled, cancelled_for_teachers = False, False
-        if SubstitutionFlag.CANCELLED in sub.flags:
+        if SubstitutionFlag.CANCELLED.value in sub.flags:
             cancelled = True
-        elif SubstitutionFlag.CANCELLED_FOR_TEACHERS in sub.flags:
+        elif SubstitutionFlag.CANCELLED_FOR_TEACHERS.value in sub.flags:
             cancelled_for_teachers = True
 
         # Comment
diff --git a/aleksis/apps/untis/util/mysql/util.py b/aleksis/apps/untis/util/mysql/util.py
index db76b41dd2133840782a30c557c82cf69b0fa522..57c53c8a1700e4c51bf908df849a4a200ff725da 100644
--- a/aleksis/apps/untis/util/mysql/util.py
+++ b/aleksis/apps/untis/util/mysql/util.py
@@ -1,5 +1,5 @@
 import logging
-from datetime import date
+from datetime import date, datetime
 from typing import Any, Callable, Optional, Sequence, Union
 
 from django.db.models import Model, QuerySet
@@ -78,7 +78,7 @@ def clean_array(seq: Sequence, conv: Callable[[Any], Any] = lambda el: el) -> Se
     """
 
     filtered = filter(lambda el: bool(el), map(lambda el: conv(el) if el else None, seq))
-    return type(a)(filtered)
+    return type(seq)(filtered)
 
 
 def untis_split_first(s: str, conv: Callable[[Any], Any] = lambda el: el) -> Sequence: