--- a/req.py	Fri Feb 13 15:12:31 2015 +0100
+++ b/req.py	Mon Feb 16 10:21:29 2015 +0100
@@ -357,7 +357,7 @@
         for key, val in sorted(newparams.iteritems()):
             query[key] = (self.url_quote(val),)
         query = '&'.join(u'%s=%s' % (param, value)
-                         for param, values in query.items()
+                         for param, values in sorted(query.items())
                          for value in values)
         return urlunsplit((schema, netloc, path, query, fragment))