diff --git a/src/pretix/api/auth/devicesecurity.py b/src/pretix/api/auth/devicesecurity.py
index 62082f1858..bf106cfb3e 100644
--- a/src/pretix/api/auth/devicesecurity.py
+++ b/src/pretix/api/auth/devicesecurity.py
@@ -10,7 +10,7 @@ class FullAccessSecurityProfile:
 
 
 class AllowListSecurityProfile:
-    allowlist = tuple()
+    allowlist = ()
 
     def is_allowed(self, request):
         key = (request.method, f"{request.resolver_match.namespace}:{request.resolver_match.url_name}")
diff --git a/src/pretix/api/serializers/event.py b/src/pretix/api/serializers/event.py
index b7930469da..9501ae7957 100644
--- a/src/pretix/api/serializers/event.py
+++ b/src/pretix/api/serializers/event.py
@@ -309,7 +309,7 @@ class EventSerializer(I18nAwareModelSerializer):
 
         # Item Meta properties
         if item_meta_properties is not None:
-            current = [imp for imp in event.item_meta_properties.all()]
+            current = list(event.item_meta_properties.all())
             for key, value in item_meta_properties.items():
                 prop = self.item_meta_props.get(key)
                 if prop in current:
diff --git a/src/pretix/api/serializers/exporters.py b/src/pretix/api/serializers/exporters.py
index 6bf7efca01..61f8a41bcc 100644
--- a/src/pretix/api/serializers/exporters.py
+++ b/src/pretix/api/serializers/exporters.py
@@ -18,18 +18,18 @@ class FormFieldWrapperField(serializers.Field):
 
 
 simple_mappings = (
-    (forms.DateField, serializers.DateField, tuple()),
-    (forms.TimeField, serializers.TimeField, tuple()),
-    (forms.SplitDateTimeField, serializers.DateTimeField, tuple()),
-    (forms.DateTimeField, serializers.DateTimeField, tuple()),
+    (forms.DateField, serializers.DateField, ()),
+    (forms.TimeField, serializers.TimeField, ()),
+    (forms.SplitDateTimeField, serializers.DateTimeField, ()),
+    (forms.DateTimeField, serializers.DateTimeField, ()),
     (forms.DecimalField, serializers.DecimalField, ('max_digits', 'decimal_places', 'min_value', 'max_value')),
-    (forms.FloatField, serializers.FloatField, tuple()),
-    (forms.IntegerField, serializers.IntegerField, tuple()),
-    (forms.EmailField, serializers.EmailField, tuple()),
-    (forms.UUIDField, serializers.UUIDField, tuple()),
-    (forms.URLField, serializers.URLField, tuple()),
-    (forms.NullBooleanField, serializers.NullBooleanField, tuple()),
-    (forms.BooleanField, serializers.BooleanField, tuple()),
+    (forms.FloatField, serializers.FloatField, ()),
+    (forms.IntegerField, serializers.IntegerField, ()),
+    (forms.EmailField, serializers.EmailField, ()),
+    (forms.UUIDField, serializers.UUIDField, ()),
+    (forms.URLField, serializers.URLField, ()),
+    (forms.NullBooleanField, serializers.NullBooleanField, ()),
+    (forms.BooleanField, serializers.BooleanField, ()),
 )
 
 
diff --git a/src/pretix/api/views/device.py b/src/pretix/api/views/device.py
index c8c89bd8d4..0a7fbe782f 100644
--- a/src/pretix/api/views/device.py
+++ b/src/pretix/api/views/device.py
@@ -53,8 +53,8 @@ class DeviceSerializer(serializers.ModelSerializer):
 
 
 class InitializeView(APIView):
-    authentication_classes = tuple()
-    permission_classes = tuple()
+    authentication_classes = ()
+    permission_classes = ()
 
     def post(self, request, format=None):
         serializer = InitializationRequestSerializer(data=request.data)
diff --git a/src/pretix/base/forms/questions.py b/src/pretix/base/forms/questions.py
index 6b86a46cde..fc6e662cd6 100644
--- a/src/pretix/base/forms/questions.py
+++ b/src/pretix/base/forms/questions.py
@@ -100,7 +100,7 @@ class NamePartsWidget(forms.MultiWidget):
         if not isinstance(value, list):
             value = self.decompress(value)
         output = []
-        final_attrs = self.build_attrs(attrs or dict())
+        final_attrs = self.build_attrs(attrs or {})
         if 'required' in final_attrs:
             del final_attrs['required']
         id_ = final_attrs.get('id', None)
diff --git a/src/pretix/base/services/cart.py b/src/pretix/base/services/cart.py
index fc42199097..7f6a734116 100644
--- a/src/pretix/base/services/cart.py
+++ b/src/pretix/base/services/cart.py
@@ -241,7 +241,7 @@ class CartManager:
                 raise CartError(_(error_messages['max_items']) % (self.event.settings.max_items_per_order,))
 
     def _check_item_constraints(self, op, current_ops=[]):
-        if isinstance(op, self.AddOperation) or isinstance(op, self.ExtendOperation):
+        if isinstance(op, (self.AddOperation, self.ExtendOperation)):
             if not (
                 (isinstance(op, self.AddOperation) and op.addon_to == 'FAKE') or
                 (isinstance(op, self.ExtendOperation) and op.position.is_bundled)
@@ -863,7 +863,7 @@ class CartManager:
                 op.position.addons.all().delete()
                 op.position.delete()
 
-            elif isinstance(op, self.AddOperation) or isinstance(op, self.ExtendOperation):
+            elif isinstance(op, (self.AddOperation, self.ExtendOperation)):
                 # Create a CartPosition for as much items as we can
                 requested_count = quota_available_count = voucher_available_count = op.count
 
diff --git a/src/pretix/base/templatetags/money.py b/src/pretix/base/templatetags/money.py
index a06d3a1634..bae229ca25 100644
--- a/src/pretix/base/templatetags/money.py
+++ b/src/pretix/base/templatetags/money.py
@@ -11,7 +11,7 @@ register = template.Library()
 
 @register.filter("money")
 def money_filter(value: Decimal, arg='', hide_currency=False):
-    if isinstance(value, float) or isinstance(value, int):
+    if isinstance(value, (float, int)):
         value = Decimal(value)
     if not isinstance(value, Decimal):
         if value == '':
@@ -47,7 +47,7 @@ def money_filter(value: Decimal, arg='', hide_currency=False):
 
 @register.filter("money_numberfield")
 def money_numberfield_filter(value: Decimal, arg=''):
-    if isinstance(value, float) or isinstance(value, int):
+    if isinstance(value, (float, int)):
         value = Decimal(value)
     if not isinstance(value, Decimal):
         raise TypeError("Invalid data type passed to money filter: %r" % type(value))
diff --git a/src/pretix/base/views/errors.py b/src/pretix/base/views/errors.py
index a0958d5718..f822c1728e 100644
--- a/src/pretix/base/views/errors.py
+++ b/src/pretix/base/views/errors.py
@@ -48,7 +48,7 @@ def page_not_found(request, exception):
     except (AttributeError, IndexError):
         pass
     else:
-        if isinstance(message, str) or isinstance(message, Promise):
+        if isinstance(message, (str, Promise)):
             exception_repr = str(message)
     context = {
         'request_path': request.path,
diff --git a/src/pretix/control/forms/item.py b/src/pretix/control/forms/item.py
index af7d614625..bb6390d7bd 100644
--- a/src/pretix/control/forms/item.py
+++ b/src/pretix/control/forms/item.py
@@ -337,7 +337,7 @@ class ItemCreateForm(I18nModelForm):
                 setattr(self.instance, f, getattr(self.cleaned_data['copy_from'], f))
         else:
             # Add to all sales channels by default
-            self.instance.sales_channels = [k for k in get_all_sales_channels().keys()]
+            self.instance.sales_channels = list(get_all_sales_channels().keys())
 
         self.instance.position = (self.event.items.aggregate(p=Max('position'))['p'] or 0) + 1
         instance = super().save(*args, **kwargs)
diff --git a/src/pretix/control/permissions.py b/src/pretix/control/permissions.py
index 3d2863b4ed..57eb090241 100644
--- a/src/pretix/control/permissions.py
+++ b/src/pretix/control/permissions.py
@@ -7,7 +7,7 @@ from django.utils.translation import gettext as _
 
 
 def current_url(request):
-    if len(request.GET):
+    if request.GET:
         return request.path + '?' + request.GET.urlencode()
     else:
         return request.path
diff --git a/src/pretix/control/views/event.py b/src/pretix/control/views/event.py
index 3debf0ada6..ad61d57db8 100644
--- a/src/pretix/control/views/event.py
+++ b/src/pretix/control/views/event.py
@@ -1363,7 +1363,7 @@ class QuickSetupView(FormView):
                 tax_rule=tax_rule,
                 admission=True,
                 position=i,
-                sales_channels=[k for k in get_all_sales_channels().keys()]
+                sales_channels=list(get_all_sales_channels().keys())
             )
             item.log_action('pretix.event.item.added', user=self.request.user, data=dict(f.cleaned_data))
             if f.cleaned_data['quota'] or not form.cleaned_data['total_quota']:
diff --git a/src/pretix/helpers/jsonlogic.py b/src/pretix/helpers/jsonlogic.py
index e7a8d59b68..9fbc624ce0 100644
--- a/src/pretix/helpers/jsonlogic.py
+++ b/src/pretix/helpers/jsonlogic.py
@@ -94,7 +94,7 @@ def merge(*args):
     """Implements the 'merge' operator for merging lists."""
     ret = []
     for arg in args:
-        if isinstance(arg, list) or isinstance(arg, tuple):
+        if isinstance(arg, (list, tuple)):
             ret += list(arg)
         else:
             ret.append(arg)
diff --git a/src/pretix/multidomain/templatetags/eventurl.py b/src/pretix/multidomain/templatetags/eventurl.py
index a87c4c44d1..5b5ae6f2f6 100644
--- a/src/pretix/multidomain/templatetags/eventurl.py
+++ b/src/pretix/multidomain/templatetags/eventurl.py
@@ -63,7 +63,7 @@ def eventurl(parser, token, absolute=False):
         asvar = bits[-1]
         bits = bits[:-2]
 
-    if len(bits):
+    if bits:
         for bit in bits:
             match = kwarg_re.match(bit)
             if not match:
diff --git a/src/pretix/plugins/checkinlists/exporters.py b/src/pretix/plugins/checkinlists/exporters.py
index d7a4a8ec65..1c7d364137 100644
--- a/src/pretix/plugins/checkinlists/exporters.py
+++ b/src/pretix/plugins/checkinlists/exporters.py
@@ -159,7 +159,7 @@ class CheckInListMixin(BaseExporter):
             ), self.event.timezone)
             qs = qs.filter(subevent__date_from__lt=dt)
 
-        o = tuple()
+        o = ()
         if self.event.has_subevents and not cl.subevent:
             o = ('subevent__date_from', 'subevent__name')
 
diff --git a/src/pretix/plugins/reports/exporters.py b/src/pretix/plugins/reports/exporters.py
index 4812003762..0b2a86f102 100644
--- a/src/pretix/plugins/reports/exporters.py
+++ b/src/pretix/plugins/reports/exporters.py
@@ -616,7 +616,7 @@ class OrderTaxListReport(MultiSheetListExporter):
         elif sheet == 'companies':
             yield from self.iterate_companies(form_data)
 
-    def _combine(self, *qs, keys=tuple()):
+    def _combine(self, *qs, keys=()):
         cache = {}
 
         def kf(r):
diff --git a/src/tests/api/test_events.py b/src/tests/api/test_events.py
index 0146980f99..94c9863d4d 100644
--- a/src/tests/api/test_events.py
+++ b/src/tests/api/test_events.py
@@ -19,7 +19,7 @@ from pretix.testutils.mock import mocker_context
 
 @pytest.fixture
 def variations(item):
-    v = list()
+    v = []
     v.append(item.variations.create(value="ChildA1"))
     v.append(item.variations.create(value="ChildA2"))
     return v
diff --git a/src/tests/api/test_items.py b/src/tests/api/test_items.py
index 9ad66fc46f..6851444f07 100644
--- a/src/tests/api/test_items.py
+++ b/src/tests/api/test_items.py
@@ -1055,7 +1055,7 @@ def test_items_with_cart_position_delete(token_client, organizer, event, item, c
 
 @pytest.fixture
 def variations(item):
-    v = list()
+    v = []
     v.append(item.variations.create(value="ChildA1"))
     v.append(item.variations.create(value="ChildA2"))
     return v
@@ -1063,7 +1063,7 @@ def variations(item):
 
 @pytest.fixture
 def variations2(item2):
-    v = list()
+    v = []
     v.append(item2.variations.create(value="ChildB1"))
     v.append(item2.variations.create(value="ChildB2"))
     return v
diff --git a/src/tests/api/test_subevents.py b/src/tests/api/test_subevents.py
index 1c0043fd82..f7c97730ca 100644
--- a/src/tests/api/test_subevents.py
+++ b/src/tests/api/test_subevents.py
@@ -15,7 +15,7 @@ from pretix.base.models.orders import OrderFee
 
 @pytest.fixture
 def variations(item):
-    v = list()
+    v = []
     v.append(item.variations.create(value="ChildA1", default_price='12.00'))
     v.append(item.variations.create(value="ChildA2", default_price='13.00'))
     return v
@@ -23,7 +23,7 @@ def variations(item):
 
 @pytest.fixture
 def variations2(item2):
-    v = list()
+    v = []
     v.append(item2.variations.create(value="ChildB1", default_price='12.00'))
     v.append(item2.variations.create(value="ChildB2", default_price='13.00'))
     return v