diff -r 6b3523f81f42 -r 26744ad37953 cubicweb/web/uihelper.py
--- a/cubicweb/web/uihelper.py	Fri Apr 05 17:21:14 2019 +0200
+++ b/cubicweb/web/uihelper.py	Fri Apr 05 17:58:19 2019 +0200
@@ -45,8 +45,6 @@
 """
 
 
-from six import add_metaclass
-
 from logilab.common.deprecation import deprecated
 from cubicweb.web.views import uicfg
 
@@ -94,8 +92,7 @@
         super(meta_formconfig, cls).__init__(name, bases, classdict)
 
 
-@add_metaclass(meta_formconfig)
-class FormConfig:
+class FormConfig(metaclass=meta_formconfig):
     """helper base class to define uicfg rules on a given entity type.
 
     In all descriptions below, attributes list can either be a list of