diff --git a/modules/purchase_trade/purchase.py b/modules/purchase_trade/purchase.py
index cc2f537..e79cf8c 100755
--- a/modules/purchase_trade/purchase.py
+++ b/modules/purchase_trade/purchase.py
@@ -795,7 +795,8 @@ class PayableRule(ModelSQL, ModelView):
             by_deduction = grade - self.deduction_value
             if self.deduction_unit.symbol == 'g/t':
                 result = min(by_percent/Decimal(10000), by_deduction/Decimal(10000))    
-            result = min(by_percent, by_deduction)
+            else:
+                result = min(by_percent, by_deduction)
 
         if self.min_payable is not None:
             result = max(result, self.min_payable)