diff --git a/keystoneauth1/adapter.py b/keystoneauth1/adapter.py
index 21497920..65c6efa2 100644
--- a/keystoneauth1/adapter.py
+++ b/keystoneauth1/adapter.py
@@ -56,6 +56,9 @@ class Adapter(object):
                                user_agent.
     """
 
+    client_name = None
+    client_version = None
+
     @positional()
     def __init__(self, session, service_type=None, service_name=None,
                  interface=None, region_name=None, endpoint_override=None,
@@ -80,10 +83,13 @@ class Adapter(object):
         self.connect_retries = connect_retries
         self.logger = logger
         self.allow = allow
-        self.client_name = client_name
-        self.client_version = client_version
         self.additional_headers = additional_headers or {}
 
+        if client_name:
+            self.client_name = client_name
+        if client_version:
+            self.client_version = client_version
+
     def _set_endpoint_filter_kwargs(self, kwargs):
         if self.service_type:
             kwargs.setdefault('service_type', self.service_type)
diff --git a/keystoneauth1/tests/unit/test_session.py b/keystoneauth1/tests/unit/test_session.py
index deba09c4..de4c564a 100644
--- a/keystoneauth1/tests/unit/test_session.py
+++ b/keystoneauth1/tests/unit/test_session.py
@@ -1039,6 +1039,25 @@ class AdapterTest(utils.TestCase):
         self.assertEqual(agent + ' ' + client_session.DEFAULT_USER_AGENT,
                          self.requests_mock.last_request.headers['User-Agent'])
 
+    def test_adapter_user_agent_session_version_on_adapter(self):
+
+        class TestAdapter(adapter.Adapter):
+
+            client_name = 'testclient'
+            client_version = '4.5.6'
+
+        sess = client_session.Session(app_name='ksatest', app_version='1.2.3')
+        adap = TestAdapter(session=sess)
+
+        url = 'http://keystone.test.com'
+        self.requests_mock.get(url)
+
+        adap.get(url)
+
+        agent = 'ksatest/1.2.3 testclient/4.5.6'
+        self.assertEqual(agent + ' ' + client_session.DEFAULT_USER_AGENT,
+                         self.requests_mock.last_request.headers['User-Agent'])
+
     def test_adapter_user_agent_session_adapter_no_app_version(self):
         sess = client_session.Session(app_name='ksatest')
         adap = adapter.Adapter(client_name='testclient',