diff --git a/venus/api/middleware/fault.py b/venus/api/middleware/fault.py
index 61e08f3..0b15ec8 100644
--- a/venus/api/middleware/fault.py
+++ b/venus/api/middleware/fault.py
@@ -13,7 +13,6 @@
 # under the License.
 
 from oslo_log import log as logging
-import six
 import webob.dec
 import webob.exc
 
@@ -61,7 +60,7 @@ class FaultWrapper(base_wsgi.Middleware):
         # including those that are safe to expose, see bug 1021373
         if safe:
             msg = (inner.msg if isinstance(inner, exception.VenusException)
-                   else six.text_type(inner))
+                   else str(inner))
             params = {'exception': inner.__class__.__name__,
                       'explanation': msg}
             outer.explanation = _('%(exception)s: %(explanation)s') % params