diff --git a/commission.py b/commission.py
index 6ddabdc..849d5b9 100644
--- a/commission.py
+++ b/commission.py
@@ -6,7 +6,6 @@ from trytond.pool import PoolMeta
 
 
 __all__ = ['AgentZipCode', 'Agent']
-__metaclass__ = PoolMeta
 
 
 class AgentZipCode(ModelSQL, ModelView):
@@ -25,5 +24,6 @@ class AgentZipCode(ModelSQL, ModelView):
 
 
 class Agent:
+    __metaclass__ = PoolMeta
     __name__ = 'commission.agent'
     zip_codes = fields.One2Many('agent.zip.code', 'agent', 'Zip Codes')
diff --git a/sale.py b/sale.py
index 140f399..5b74f5a 100644
--- a/sale.py
+++ b/sale.py
@@ -9,10 +9,10 @@ from sql.operators import Like
 
 
 __all__ = ['Sale']
-__metaclass__ = PoolMeta
 
 
 class Sale:
+    __metaclass__ = PoolMeta
     __name__ = 'sale.sale'
 
     @fields.depends('party', 'shipment_address')