diff --git a/tripleo_common/actions/baremetal.py b/tripleo_common/actions/baremetal.py
index 4c0a93268..dc73355ec 100644
--- a/tripleo_common/actions/baremetal.py
+++ b/tripleo_common/actions/baremetal.py
@@ -256,7 +256,7 @@ class ConfigureRootDeviceAction(base.TripleOAction):
                     {'strategy': strategy, 'node': node.uuid})
 
         hint = None
-        for hint_name in ('wwn', 'serial'):
+        for hint_name in ('wwn_with_extension', 'wwn', 'serial'):
             if root_device.get(hint_name):
                 hint = {hint_name: root_device[hint_name]}
                 break
diff --git a/tripleo_common/tests/actions/test_baremetal.py b/tripleo_common/tests/actions/test_baremetal.py
index 6d2079a5f..5f313397d 100644
--- a/tripleo_common/tests/actions/test_baremetal.py
+++ b/tripleo_common/tests/actions/test_baremetal.py
@@ -202,6 +202,21 @@ class TestConfigureRootDeviceAction(base.TestCase):
         self.assertEqual(mock.call('ABCDEFGH', expected_patch),
                          root_device_args)
 
+    def test_smallest_with_ext(self):
+        self.disks[2]['wwn_with_extension'] = 'wwnext'
+        action = baremetal.ConfigureRootDeviceAction(node_uuid='MOCK_UUID',
+                                                     root_device='smallest')
+        action.run(self.context)
+
+        self.assertEqual(self.ironic.node.update.call_count, 1)
+        root_device_args = self.ironic.node.update.call_args_list[0]
+        expected_patch = [{'op': 'add', 'path': '/properties/root_device',
+                           'value': {'wwn_with_extension': 'wwnext'}},
+                          {'op': 'add', 'path': '/properties/local_gb',
+                           'value': 4}]
+        self.assertEqual(mock.call('ABCDEFGH', expected_patch),
+                         root_device_args)
+
     def test_largest(self):
         action = baremetal.ConfigureRootDeviceAction(node_uuid='MOCK_UUID',
                                                      root_device='largest')
@@ -216,6 +231,21 @@ class TestConfigureRootDeviceAction(base.TestCase):
         self.assertEqual(mock.call('ABCDEFGH', expected_patch),
                          root_device_args)
 
+    def test_largest_with_ext(self):
+        self.disks[3]['wwn_with_extension'] = 'wwnext'
+        action = baremetal.ConfigureRootDeviceAction(node_uuid='MOCK_UUID',
+                                                     root_device='largest')
+        action.run(self.context)
+
+        self.assertEqual(self.ironic.node.update.call_count, 1)
+        root_device_args = self.ironic.node.update.call_args_list[0]
+        expected_patch = [{'op': 'add', 'path': '/properties/root_device',
+                           'value': {'wwn_with_extension': 'wwnext'}},
+                          {'op': 'add', 'path': '/properties/local_gb',
+                           'value': 20}]
+        self.assertEqual(mock.call('ABCDEFGH', expected_patch),
+                         root_device_args)
+
     def test_no_overwrite(self):
         self.node.properties['root_device'] = {'foo': 'bar'}