diff --git a/google/auth/_helpers.py b/google/auth/_helpers.py
index f321bc834..e7e5d97cf 100644
--- a/google/auth/_helpers.py
+++ b/google/auth/_helpers.py
@@ -92,7 +92,14 @@ def utcnow():
     Returns:
         datetime: The current time in UTC.
     """
-    return datetime.datetime.utcnow()
+    # We used datetime.utcnow() before, since it's deprecated from python 3.12,
+    # we are using datetime.now(timezone.utc) now. "utcnow()" is offset-native
+    # (no timezone info), but "now()" is offset-aware (with timezone info).
+    # This will cause datetime comparison problem. For backward compatibility,
+    # we need to remove the timezone info.
+    now = datetime.datetime.now(datetime.timezone.utc)
+    now = now.replace(tzinfo=None)
+    return now
 
 
 def datetime_to_secs(value):
diff --git a/tests/test_credentials.py b/tests/test_credentials.py
index 5eee35c98..d64f3abb5 100644
--- a/tests/test_credentials.py
+++ b/tests/test_credentials.py
@@ -55,9 +55,7 @@ def test_expired_and_valid():
     # Set the expiration to one second more than now plus the clock skew
     # accomodation. These credentials should be valid.
     credentials.expiry = (
-        datetime.datetime.utcnow()
-        + _helpers.REFRESH_THRESHOLD
-        + datetime.timedelta(seconds=1)
+        _helpers.utcnow() + _helpers.REFRESH_THRESHOLD + datetime.timedelta(seconds=1)
     )
 
     assert credentials.valid
@@ -65,7 +63,7 @@ def test_expired_and_valid():
 
     # Set the credentials expiration to now. Because of the clock skew
     # accomodation, these credentials should report as expired.
-    credentials.expiry = datetime.datetime.utcnow()
+    credentials.expiry = _helpers.utcnow()
 
     assert not credentials.valid
     assert credentials.expired
diff --git a/tests_async/test_credentials_async.py b/tests_async/test_credentials_async.py
index 9db5fc9ae..7d82758c3 100644
--- a/tests_async/test_credentials_async.py
+++ b/tests_async/test_credentials_async.py
@@ -46,9 +46,7 @@ def test_expired_and_valid():
     # Set the expiration to one second more than now plus the clock skew
     # accomodation. These credentials should be valid.
     credentials.expiry = (
-        datetime.datetime.utcnow()
-        + _helpers.REFRESH_THRESHOLD
-        + datetime.timedelta(seconds=1)
+        _helpers.utcnow() + _helpers.REFRESH_THRESHOLD + datetime.timedelta(seconds=1)
     )
 
     assert credentials.valid
@@ -56,7 +54,7 @@ def test_expired_and_valid():
 
     # Set the credentials expiration to now. Because of the clock skew
     # accomodation, these credentials should report as expired.
-    credentials.expiry = datetime.datetime.utcnow()
+    credentials.expiry = _helpers.utcnow()
 
     assert not credentials.valid
     assert credentials.expired