diff --git a/erpnext/controllers/taxes_and_totals.py b/erpnext/controllers/taxes_and_totals.py
index d8b5e2e..2369143 100644
--- a/erpnext/controllers/taxes_and_totals.py
+++ b/erpnext/controllers/taxes_and_totals.py
@@ -338,7 +338,7 @@
 			tax.item_wise_tax_detail = json.dumps(tax.item_wise_tax_detail, separators=(',', ':'))
 
 	def set_discount_amount(self):
-		if not self.doc.discount_amount and self.doc.additional_discount_percentage:
+		if self.doc.additional_discount_percentage:
 			self.doc.discount_amount = flt(flt(self.doc.get(scrub(self.doc.apply_discount_on)))
 				* self.doc.additional_discount_percentage / 100, self.doc.precision("discount_amount"))