diff --git a/b2sdk/_internal/b2http.py b/b2sdk/_internal/b2http.py
index 8deb3fc0..0d0fe031 100644
--- a/b2sdk/_internal/b2http.py
+++ b/b2sdk/_internal/b2http.py
@@ -145,15 +145,20 @@ def post_request(self, method, url, headers, response):
         # Convert the server time to a datetime object
         try:
             with setlocale("C"):
+                # "%Z" always creates naive datetimes, even though the timezone
+                # is specified. https://github.com/python/cpython/issues/76678
+                # Anyway, thankfully, HTTP/1.1 spec requires the string
+                # to always say "GMT", and provide UTC time.
+                # https://datatracker.ietf.org/doc/html/rfc2616#section-3.3.1
                 server_time = datetime.datetime.strptime(
-                    server_date_str, '%a, %d %b %Y %H:%M:%S %Z'
-                )
+                    server_date_str, '%a, %d %b %Y %H:%M:%S GMT'
+                ).replace(tzinfo=datetime.timezone.utc)
         except ValueError:
             logger.exception('server returned date in an inappropriate format')
             raise BadDateFormat(server_date_str)
 
         # Get the local time
-        local_time = datetime.datetime.utcnow()
+        local_time = datetime.datetime.now(datetime.timezone.utc)
 
         # Check the difference.
         max_allowed = 10 * 60  # ten minutes, in seconds
diff --git a/changelog.d/+datetime.utcnow_deprecation.fixed.md b/changelog.d/+datetime.utcnow_deprecation.fixed.md
new file mode 100644
index 00000000..ceb598f6
--- /dev/null
+++ b/changelog.d/+datetime.utcnow_deprecation.fixed.md
@@ -0,0 +1 @@
+Fixed datetime.utcnow() deprecation warnings in Python 3.12.
diff --git a/test/unit/b2http/test_b2http.py b/test/unit/b2http/test_b2http.py
index f8f7602c..40079ea4 100644
--- a/test/unit/b2http/test_b2http.py
+++ b/test/unit/b2http/test_b2http.py
@@ -402,14 +402,14 @@ def test_bad_month(self):
             ClockSkewHook().post_request('POST', 'http://example.com', {}, response)
 
     def test_no_skew(self):
-        now = datetime.datetime.utcnow()
+        now = datetime.datetime.now(datetime.timezone.utc)
         now_str = now.strftime('%a, %d %b %Y %H:%M:%S GMT')
         response = MagicMock()
         response.headers = {'Date': now_str}
         ClockSkewHook().post_request('POST', 'http://example.com', {}, response)
 
     def test_positive_skew(self):
-        now = datetime.datetime.utcnow() + datetime.timedelta(minutes=11)
+        now = datetime.datetime.now(datetime.timezone.utc) + datetime.timedelta(minutes=11)
         now_str = now.strftime('%a, %d %b %Y %H:%M:%S GMT')
         response = MagicMock()
         response.headers = {'Date': now_str}
@@ -417,7 +417,7 @@ def test_positive_skew(self):
             ClockSkewHook().post_request('POST', 'http://example.com', {}, response)
 
     def test_negative_skew(self):
-        now = datetime.datetime.utcnow() + datetime.timedelta(minutes=-11)
+        now = datetime.datetime.now(datetime.timezone.utc) + datetime.timedelta(minutes=-11)
         now_str = now.strftime('%a, %d %b %Y %H:%M:%S GMT')
         response = MagicMock()
         response.headers = {'Date': now_str}