diff --git a/zun/container/docker/driver.py b/zun/container/docker/driver.py
index 4e8a5737b..03b327c2b 100644
--- a/zun/container/docker/driver.py
+++ b/zun/container/docker/driver.py
@@ -396,9 +396,10 @@ class DockerDriver(driver.ContainerDriver):
 
     def _populate_command(self, container, config):
         command_list = config.get('Cmd')
-        command_str = ' '.join(command_list)
-        if command_str:
-            container.command = command_str
+        command_str = None
+        if command_list:
+            command_str = ' '.join(command_list)
+        container.command = command_str
 
     def _populate_hostname_and_ports(self, container, config):
         # populate hostname only when container.hostname wasn't set
diff --git a/zun/tests/unit/container/docker/test_docker_driver.py b/zun/tests/unit/container/docker/test_docker_driver.py
index 9db8160d9..ffb6da8a9 100644
--- a/zun/tests/unit/container/docker/test_docker_driver.py
+++ b/zun/tests/unit/container/docker/test_docker_driver.py
@@ -189,6 +189,16 @@ class TestDockerDriver(base.DriverTestCase):
             mock_container.container_id)
         self.assertEqual('fake_command', mock_container.command)
 
+    def test_show_without_command(self):
+        self.mock_docker.inspect_container = mock.Mock(
+            return_value={'State': 'running',
+                          'Config': {'Cmd': None}})
+        mock_container = mock.MagicMock()
+        self.driver.show(self.context, mock_container)
+        self.mock_docker.inspect_container.assert_called_once_with(
+            mock_container.container_id)
+        self.assertIsNone(mock_container.command)
+
     def test_show_fail_container_id_is_none(self):
         mock_container = mock.MagicMock()
         mock_container.container_id = None