diff --git a/addons/analytic/analytic.py b/addons/analytic/analytic.py
index 7b5cc275377..5a77b86f14f 100644
--- a/addons/analytic/analytic.py
+++ b/addons/analytic/analytic.py
@@ -219,7 +219,7 @@ class account_analytic_account(osv.osv):
         res['value']['description'] = template.description
         return res
 
-    def on_change_partner_id(self, cr, uid, ids,partner_id, name, context={}):
+    def on_change_partner_id(self, cr, uid, ids,partner_id, name, context=None):
         res={}
         if partner_id:
             partner = self.pool.get('res.partner').browse(cr, uid, partner_id, context=context)