diff --git a/modules/purchase_trade/fee.py b/modules/purchase_trade/fee.py
index 99bf636..31c8cb0 100755
--- a/modules/purchase_trade/fee.py
+++ b/modules/purchase_trade/fee.py
@@ -120,6 +120,7 @@ class Fee(ModelSQL,ModelView):
             logger.info("ON_CHANGE_WITH_LOTS:%s",lots)
             if lots:
                 qt = sum([e.get_current_quantity() for e in lots])
+                unit = lots[0].lot_unit_line
         if not qt:
             logger.info("ON_CHANGE_WITH_QT1:%s",qt)
             LotQt = Pool().get('lot.qt')