diff --git a/gisserver/output/csv.py b/gisserver/output/csv.py
index 1219630..5ef6c11 100644
--- a/gisserver/output/csv.py
+++ b/gisserver/output/csv.py
@@ -2,11 +2,10 @@
 from __future__ import annotations
 
 import csv
-from datetime import datetime
+from datetime import datetime, timezone
 
 from django.conf import settings
 from django.db import models
-from django.utils.timezone import utc
 
 from gisserver import conf
 from gisserver.db import (
@@ -137,7 +136,7 @@ def get_row(self, instance: models.Model, fields: list[XsdElement]):
                 # Array field
                 append(",".join(map(str, value)))
             elif isinstance(value, datetime):
-                append(str(value.astimezone(utc)))
+                append(str(value.astimezone(timezone.utc)))
             else:
                 append(value)
         return values
diff --git a/gisserver/output/geojson.py b/gisserver/output/geojson.py
index 50efce2..5a20135 100644
--- a/gisserver/output/geojson.py
+++ b/gisserver/output/geojson.py
@@ -1,5 +1,5 @@
 """Output rendering logic for GeoJSON."""
-from datetime import datetime
+from datetime import datetime, timezone
 from decimal import Decimal
 from typing import cast
 
@@ -8,7 +8,6 @@
 from django.contrib.gis.db.models.functions import AsGeoJSON
 from django.db import models
 from django.utils.functional import Promise
-from django.utils.timezone import utc
 
 from gisserver import conf
 from gisserver.db import get_db_geometry_target
@@ -147,7 +146,7 @@ def render_feature(
 
     def _format_geojson_value(self, value):
         if isinstance(value, datetime):
-            return value.astimezone(utc)
+            return value.astimezone(timezone.utc)
         elif isinstance(value, models.Model):
             # ForeignKey, not defined as complex type.
             return str(value)
diff --git a/gisserver/output/gml32.py b/gisserver/output/gml32.py
index b21c28f..d02df9a 100644
--- a/gisserver/output/gml32.py
+++ b/gisserver/output/gml32.py
@@ -7,14 +7,13 @@
 
 import itertools
 import re
-from datetime import date, datetime, time
+from datetime import date, datetime, time, timezone
 from html import escape
 from typing import cast
 
 from django.contrib.gis import geos
 from django.db import models
 from django.http import HttpResponse
-from django.utils.timezone import utc
 
 from gisserver.db import (
     AsGML,
@@ -306,7 +305,7 @@ def _render_xml_field(
             # Expanded foreign relation / dictionary
             return self.render_xml_complex_type(feature_type, xsd_element, value)
         elif isinstance(value, datetime):
-            value = value.astimezone(utc).isoformat()
+            value = value.astimezone(timezone.utc).isoformat()
         elif isinstance(value, (date, time)):
             value = value.isoformat()
         elif isinstance(value, bool):
diff --git a/gisserver/output/results.py b/gisserver/output/results.py
index 9b8f98d..197f8c1 100644
--- a/gisserver/output/results.py
+++ b/gisserver/output/results.py
@@ -13,7 +13,9 @@
 import django
 from django.db import models
 from django.utils.functional import cached_property
-from django.utils.timezone import now, utc
+from django.utils.timezone import now
+
+from datetime import timezone
 
 from gisserver.features import FeatureType
 from gisserver.geometries import BoundingBox
@@ -218,7 +220,7 @@ def __init__(
         self.next = next
         self.previous = previous
         self.date = now()
-        self.timestamp = self.date.astimezone(utc).isoformat()
+        self.timestamp = self.date.astimezone(timezone.utc).isoformat()
 
     def get_bounding_box(self) -> BoundingBox:
         """Determine bounding box of all items."""
diff --git a/tests/test_gisserver/models.py b/tests/test_gisserver/models.py
index a9c9e6b..92eb6b1 100644
--- a/tests/test_gisserver/models.py
+++ b/tests/test_gisserver/models.py
@@ -4,11 +4,11 @@
 from django.contrib.gis.db.models import PointField
 from django.contrib.postgres.fields import ArrayField
 from django.db import models
-from django.utils.timezone import utc
 
+from datetime import timezone
 
 def current_datetime():
-    return datetime(2020, 4, 5, 12, 11, 10, 0, tzinfo=utc)
+    return datetime(2020, 4, 5, 12, 11, 10, 0, tzinfo=timezone.utc)
 
 
 class City(models.Model):