diff --git a/python/ovs/unixctl/__init__.py b/python/ovs/unixctl/__init__.py
index 26e126a97..d3d35562b 100644
--- a/python/ovs/unixctl/__init__.py
+++ b/python/ovs/unixctl/__init__.py
@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import types
-
 import six
 
 import ovs.util
@@ -63,7 +61,7 @@ def command_register(name, usage, min_args, max_args, callback, aux):
     assert isinstance(usage, strtypes)
     assert isinstance(min_args, int)
     assert isinstance(max_args, int)
-    assert isinstance(callback, types.FunctionType)
+    assert callable(callback)
 
     if name not in commands:
         commands[name] = _UnixctlCommand(usage, min_args, max_args, callback,