diff --git a/addons/product_margin/wizard/product_margin.py b/addons/product_margin/wizard/product_margin.py
index 61137a5e51e..cdabc8f9964 100644
--- a/addons/product_margin/wizard/product_margin.py
+++ b/addons/product_margin/wizard/product_margin.py
@@ -64,11 +64,11 @@ class product_margin(osv.osv_memory):
         #get the current product.margin object to obtain the values from it
         product_margin_obj = self.browse(cr, uid, ids, context=context)[0]
 
-        context = {'invoice_state' : product_margin_obj.invoice_state}
+        context.update(invoice_state = product_margin_obj.invoice_state)
         if product_margin_obj.from_date:
-            context.update({'date_from': product_margin_obj.from_date})
+            context.update(date_from = product_margin_obj.from_date)
         if product_margin_obj.to_date:
-            context.update({'date_to': product_margin_obj.to_date})
+            context.update(date_to = product_margin_obj.to_date)
         return {
             'name': _('Product Margins'),
             'context': context,