diff --git a/automatoes/issue.py b/automatoes/issue.py
index d8c54da..1cfbc21 100644
--- a/automatoes/issue.py
+++ b/automatoes/issue.py
@@ -188,7 +188,7 @@ def issue(server, paths, account, domains, key_size, key_file=None,
         certificate = load_pem_certificate(certificates[0])
 
         # Print some neat info
-        print("  Expires: {}".format(certificate.not_valid_after.strftime(
+        print("  Expires: {}".format(certificate.not_valid_after_utc.strftime(
             EXPIRATION_FORMAT)))
         print("   SHA256: {}".format(binascii.hexlify(
             certificate.fingerprint(SHA256())).decode('ascii')))
diff --git a/tests/issue_test.py b/tests/issue_test.py
new file mode 100644
index 0000000..8837f65
--- /dev/null
+++ b/tests/issue_test.py
@@ -0,0 +1,79 @@
+#!/usr/bin/env python
+#
+# Copyright 2019-2025 Flavio Garcia
+# Copyright 2016-2017 Veeti Paananen under MIT License
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from unittest.mock import patch, MagicMock
+from cryptography import x509
+from cryptography.hazmat.primitives import serialization, hashes
+from cryptography.hazmat.primitives.asymmetric import rsa
+import datetime
+import warnings
+
+from automatoes.issue import EXPIRATION_FORMAT
+
+
+class IssueTestCase(unittest.TestCase):
+
+    def test_certificate_expiration_uses_utc_property(self):
+        """Test that certificate expiration formatting uses not_valid_after_utc."""
+        # Generate a test certificate
+        private_key = rsa.generate_private_key(
+            public_exponent=65537,
+            key_size=2048,
+        )
+        
+        subject = issuer = x509.Name([
+            x509.NameAttribute(x509.NameOID.COUNTRY_NAME, 'US'),
+            x509.NameAttribute(x509.NameOID.COMMON_NAME, 'test.example.com'),
+        ])
+        
+        # Create expiration date in UTC
+        expiration_date = datetime.datetime(2025, 12, 31, 23, 59, 59, tzinfo=datetime.timezone.utc)
+        
+        cert = x509.CertificateBuilder().subject_name(
+            subject
+        ).issuer_name(
+            issuer
+        ).public_key(
+            private_key.public_key()
+        ).serial_number(
+            x509.random_serial_number()
+        ).not_valid_before(
+            datetime.datetime.now()
+        ).not_valid_after(
+            expiration_date
+        ).sign(private_key, hashes.SHA256())
+        
+        # Test that not_valid_after_utc returns UTC-aware datetime
+        self.assertIsNotNone(cert.not_valid_after_utc)
+        self.assertIsNotNone(cert.not_valid_after_utc.tzinfo)
+        
+        # Test that formatting works correctly with not_valid_after_utc
+        formatted_expiration = cert.not_valid_after_utc.strftime(EXPIRATION_FORMAT)
+        self.assertEqual(formatted_expiration, "2025-12-31")
+        
+        # Test that not_valid_after (deprecated) produces warnings
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            _ = cert.not_valid_after
+            # Check that a deprecation warning was issued
+            self.assertTrue(len(w) > 0)
+            self.assertTrue(any("deprecated" in str(warning.message).lower() for warning in w))
+
+
+if __name__ == "__main__":
+    unittest.main()
\ No newline at end of file
diff --git a/tests/runtests.py b/tests/runtests.py
index cf289a8..2bbac6f 100644
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -15,13 +15,14 @@
 # limitations under the License.
 
 import unittest
-from tests import crypto_test
+from tests import crypto_test, issue_test
 
 
 def suite():
     testLoader = unittest.TestLoader()
     alltests = unittest.TestSuite()
     alltests.addTests(testLoader.loadTestsFromModule(crypto_test))
+    alltests.addTests(testLoader.loadTestsFromModule(issue_test))
     return alltests