--- a/rtags.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/rtags.py	Mon Sep 14 16:03:07 2015 +0200
@@ -40,6 +40,8 @@
 import logging
 from warnings import warn
 
+from six import string_types
+
 from logilab.common.logging_ext import set_log_methods
 from logilab.common.registry import RegistrableInstance, yes
 
@@ -145,7 +147,7 @@
         return tag
 
     def _tag_etype_attr(self, etype, attr, desttype='*', *args, **kwargs):
-        if isinstance(attr, basestring):
+        if isinstance(attr, string_types):
             attr, role = attr, 'subject'
         else:
             attr, role = attr