diff --git a/modules/purchase_trade/purchase.py b/modules/purchase_trade/purchase.py
index 93c5c2b..cc2f537 100755
--- a/modules/purchase_trade/purchase.py
+++ b/modules/purchase_trade/purchase.py
@@ -793,6 +793,8 @@ class PayableRule(ModelSQL, ModelView):
         elif self.payable_method == 'min_of_both':
             by_percent = grade * self.payable_percent / Decimal(100)
             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)
 
         if self.min_payable is not None: