diff --git a/winrm/tests/test_transport.py b/winrm/tests/test_transport.py
index bfcd09b..68942ea 100644
--- a/winrm/tests/test_transport.py
+++ b/winrm/tests/test_transport.py
@@ -100,6 +100,19 @@ def test_build_session_cert_override_2(self):
         t_default.build_session()
         self.assertEqual('overridepath', t_default.session.verify)
 
+    def test_build_session_cert_override_3(self):
+        os.environ['CURL_CA_BUNDLE'] = 'path_to_CURL_CA_CERT'
+
+        t_default = transport.Transport(endpoint="https://example.com",
+                                        server_cert_validation='validate',
+                                        username='test',
+                                        password='test',
+                                        auth_method='basic',
+                                        ca_trust_path=None,
+                                        )
+        t_default.build_session()
+        self.assertEqual(True, t_default.session.verify)
+
     def test_build_session_cert_ignore_1(self):
         os.environ['REQUESTS_CA_BUNDLE'] = 'path_to_REQUESTS_CA_CERT'
         os.environ['CURL_CA_BUNDLE'] = 'path_to_CURL_CA_CERT'