diff --git a/addons/account/account.py b/addons/account/account.py
index e18df8a0d31..6368149ba5c 100644
--- a/addons/account/account.py
+++ b/addons/account/account.py
@@ -1956,15 +1956,17 @@ class account_tax(osv.osv):
         return super(account_tax, self).write(cr, uid, ids, vals, context=context)
 
     def search(self, cr, uid, args, offset=0, limit=None, order=None, context=None, count=False):
+        if context is None:
+            context = {}
         journal_pool = self.pool.get('account.journal')
 
-        if context and context.has_key('type'):
+        if context.get('type'):
             if context.get('type') in ('out_invoice','out_refund'):
                 args += [('type_tax_use','in',['sale','all'])]
             elif context.get('type') in ('in_invoice','in_refund'):
                 args += [('type_tax_use','in',['purchase','all'])]
 
-        if context and context.has_key('journal_id'):
+        if context.get('journal_id'):
             journal = journal_pool.browse(cr, uid, context.get('journal_id'))
             if journal.type in ('sale', 'purchase'):
                 args += [('type_tax_use','in',[journal.type,'all'])]