diff --git a/party.py b/party.py
index 2d0511e..e8ac3d9 100644
--- a/party.py
+++ b/party.py
@@ -7,10 +7,8 @@ from trytond.model import fields
 __all__ = ['Party', 'PartyIdentifier']
 
 
-class Party:
+class Party(metaclass=PoolMeta):
     __name__ = 'party.party'
-    __metaclass__ = PoolMeta
-
     accise_identifier = fields.Function(fields.Many2One(
             'party.identifier', 'Accise Identifier'),
         'get_accise_identifier', searcher='search_accise_identifier')
@@ -42,9 +40,8 @@ class Party:
         return domain
 
 
-class PartyIdentifier:
+class PartyIdentifier(metaclass=PoolMeta):
     __name__ = 'party.identifier'
-    __metaclass__ = PoolMeta
 
     @classmethod
     def get_types(cls):
diff --git a/setup.py b/setup.py
index 8c99161..0a1c428 100644
--- a/setup.py
+++ b/setup.py
@@ -7,10 +7,7 @@ from setuptools import setup
 import re
 import os
 import io
-try:
-    from configparser import ConfigParser
-except ImportError:
-    from ConfigParser import ConfigParser
+from configparser import ConfigParser
 
 MODULE2PREFIX = {}
 
diff --git a/tryton.cfg b/tryton.cfg
index 3fcaee8..19ee524 100644
--- a/tryton.cfg
+++ b/tryton.cfg
@@ -1,5 +1,5 @@
 [tryton]
-version=4.3.0
+version=4.9.0
 depends:
     ir
     party