diff --git a/addons/product/product.py b/addons/product/product.py
index 801e647e3f2..c1588c2295b 100644
--- a/addons/product/product.py
+++ b/addons/product/product.py
@@ -139,7 +139,7 @@ class product_uom(osv.osv):
             context = {}
         if from_unit.category_id.id <> to_unit.category_id.id:
             if context.get('raise-exception', True):
-                raise osv.except_osv(_('Error !'), _('Conversion from Product UoM m to Default UoM PCE is not possible as they both belong to different Category!.'))
+                raise osv.except_osv(_('Error !'), _('Conversion from Product UoM %s to Default UoM %s is not possible as they both belong to different Category!.') % (from_unit.name,to_unit.name,))
             else:
                 return qty
         amount = qty / from_unit.factor