diff --git a/aleksis/apps/untis/forms.py b/aleksis/apps/untis/forms.py
index e8f9c71286b98c184f1127666341e14e20a40919..1cf55a8b65ea3590933e9321bbac7e8d5e466601 100644
--- a/aleksis/apps/untis/forms.py
+++ b/aleksis/apps/untis/forms.py
@@ -1,11 +1,6 @@
 from django import forms
 from django.utils.translation import ugettext_lazy as _
 
-from material import Fieldset
-
-from aleksis.core.forms import EditGroupForm
-from aleksis.core.models import Group
-
 
 class UntisUploadForm(forms.Form):
     untis_xml = forms.FileField(label=_("Untis XML export"))
diff --git a/aleksis/apps/untis/model_extensions.py b/aleksis/apps/untis/model_extensions.py
index 8105b3bdc0ad6434ed56411dda9b37b8e80356df..7caa8828a375f44ec4e27f6b6c2e516db1844d58 100644
--- a/aleksis/apps/untis/model_extensions.py
+++ b/aleksis/apps/untis/model_extensions.py
@@ -1,6 +1,6 @@
 from django.utils.translation import gettext as _
 
-from jsonstore import CharField, IntegerField
+from jsonstore import IntegerField
 
 from aleksis.apps.chronos import models as chronos_models
 from aleksis.core import models as core_models
diff --git a/aleksis/apps/untis/util/mysql/importers/lessons.py b/aleksis/apps/untis/util/mysql/importers/lessons.py
index f937952113dcc20be2b0e7775a2acfee362f0d23..2eb8e9de80b81d5fd620e818fc1efd29070d038d 100644
--- a/aleksis/apps/untis/util/mysql/importers/lessons.py
+++ b/aleksis/apps/untis/util/mysql/importers/lessons.py
@@ -32,7 +32,6 @@ def import_lessons(
     classes_ref,
 ):
     """Import lessons."""
-
     # Lessons
     lessons = run_default_filter(validity_range, mysql_models.Lesson.objects)
 
@@ -102,7 +101,7 @@ def import_lessons(
             if subject_id != 0:
                 subject = subjects_ref[subject_id]
             else:
-                logger.warning(_("    Skip because missing subject".format(i)))
+                logger.warning(_("    Skip because missing subject"))
                 continue
 
             # Get classes
diff --git a/aleksis/apps/untis/util/mysql/importers/substitutions.py b/aleksis/apps/untis/util/mysql/importers/substitutions.py
index d4529770cce9a3731ba99b60fdae80d94d6a0608..8ebc0f67ae52b16bd95f3dc9a8c6c4e521e60765 100644
--- a/aleksis/apps/untis/util/mysql/importers/substitutions.py
+++ b/aleksis/apps/untis/util/mysql/importers/substitutions.py
@@ -36,7 +36,6 @@ def import_substitutions(
     time_periods_ref,
 ):
     """Import substitutions."""
-
     subs = (
         run_default_filter(
             validity_range, mysql_models.Substitution.objects, filter_term=False
diff --git a/aleksis/apps/untis/util/mysql/importers/terms.py b/aleksis/apps/untis/util/mysql/importers/terms.py
index 3a547ad1b9aae2c02392aa0a287243a1f4b0b725..dcfb9279f993349bd13bd8f01c63dc30ef93b56b 100644
--- a/aleksis/apps/untis/util/mysql/importers/terms.py
+++ b/aleksis/apps/untis/util/mysql/importers/terms.py
@@ -77,18 +77,18 @@ def import_terms(
                 school_term = core_models.SchoolTerm.objects.get(
                     import_ref_untis=school_year_id
                 )
-                logger.info(f"    School year found by import reference.")
+                logger.info("    School year found by import reference.")
             except core_models.SchoolTerm.DoesNotExist:
                 try:
                     school_term = core_models.SchoolTerm.objects.within_dates(
                         date_start, date_end
                     ).get()
-                    logger.info(f"    School year found by time.")
+                    logger.info("    School year found by time.")
                 except core_models.SchoolTerm.DoesNotExist:
                     school_term = core_models.SchoolTerm(
                         date_start=date_start, date_end=date_end, name=school_term_name
                     )
-                    logger.info(f"    School year created newly.")
+                    logger.info("    School year created newly.")
 
             school_term.import_ref_untis = school_year_id
 
@@ -104,16 +104,16 @@ def import_terms(
             validity_range = chronos_models.ValidityRange.objects.get(
                 import_ref_untis=term_id
             )
-            logger.info(f"  Validity range found by import reference.")
+            logger.info("  Validity range found by import reference.")
         except chronos_models.ValidityRange.DoesNotExist:
             try:
                 validity_range = chronos_models.ValidityRange.objects.within_dates(
                     date_start, date_end
                 ).get()
-                logger.info(f"  Validity range found by time.")
+                logger.info("  Validity range found by time.")
             except chronos_models.ValidityRange.DoesNotExist:
                 validity_range = chronos_models.ValidityRange()
-                logger.info(f"  Validity range created newly.")
+                logger.info("  Validity range created newly.")
 
         validity_range.import_ref_untis = term_id
         validity_range.date_start = date_start
diff --git a/aleksis/apps/untis/util/mysql/main.py b/aleksis/apps/untis/util/mysql/main.py
index 3787966cf21c8f66e9cecbfcfe1567d6145e95fa..66c42b25f64d2b72e34407d9c9516e45329372e8 100644
--- a/aleksis/apps/untis/util/mysql/main.py
+++ b/aleksis/apps/untis/util/mysql/main.py
@@ -1,6 +1,7 @@
 from aleksis.apps.untis.util.mysql.importers.terms import import_terms, get_terms_for_date
 from aleksis.apps.untis.util.mysql.util import TQDM_DEFAULTS
 from django.db import transaction
+
 from tqdm import tqdm
 
 from aleksis.apps.untis.util.mysql.importers.terms import (