diff --git a/blacksheep/client/cookies.py b/blacksheep/client/cookies.py
index cc4beab3..a4bb6cec 100644
--- a/blacksheep/client/cookies.py
+++ b/blacksheep/client/cookies.py
@@ -1,5 +1,5 @@
 import logging
-from datetime import datetime, timedelta
+from datetime import timedelta
 from ipaddress import ip_address
 from typing import Dict, Iterable, Optional, TypeVar
 
diff --git a/blacksheep/server/authentication/cookie.py b/blacksheep/server/authentication/cookie.py
index 2b43736c..408ad030 100644
--- a/blacksheep/server/authentication/cookie.py
+++ b/blacksheep/server/authentication/cookie.py
@@ -1,4 +1,4 @@
-from datetime import datetime
+from datetime import datetime, UTC
 from typing import Any, Optional, Sequence
 
 from guardpost import AuthenticationHandler, Identity
@@ -80,7 +80,9 @@ def set_cookie(self, data: Any, response: Response, secure: bool = False) -> Non
                 path="/",
                 http_only=True,
                 secure=secure,
-                expires=datetime.fromtimestamp(data["exp"]) if "exp" in data else None,
+                expires=(
+                    datetime.fromtimestamp(data["exp"], UTC) if "exp" in data else None
+                ),
             )
         )
 
diff --git a/blacksheep/server/openapi/common.py b/blacksheep/server/openapi/common.py
index 2fde0283..2b73269e 100644
--- a/blacksheep/server/openapi/common.py
+++ b/blacksheep/server/openapi/common.py
@@ -9,7 +9,6 @@
 import json
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
-from datetime import datetime
 from enum import Enum
 from http import HTTPStatus
 from typing import (
diff --git a/blacksheep/server/openapi/ui.py b/blacksheep/server/openapi/ui.py
index a03ce6a8..c713694c 100644
--- a/blacksheep/server/openapi/ui.py
+++ b/blacksheep/server/openapi/ui.py
@@ -1,6 +1,5 @@
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
-from datetime import datetime
 from typing import Callable
 
 from blacksheep.messages import Request, Response
diff --git a/tests/client/test_cookiejar.py b/tests/client/test_cookiejar.py
index 738992e8..dae36601 100644
--- a/tests/client/test_cookiejar.py
+++ b/tests/client/test_cookiejar.py
@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta
+from datetime import timedelta
 
 from blacksheep.utils.time import utcnow