diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index 9b473c1..09f303f 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -247,7 +247,7 @@
 	def update_item(obj, target, source_parent):
 		target.amount = flt(obj.amount) - flt(obj.billed_amt)
 		target.base_amount = target.amount * flt(source_parent.conversion_rate)
-		target.qty = target.amount / flt(obj.rate) if flt(obj.rate) else flt(obj.qty)
+		target.qty = target.amount / flt(obj.rate) if (flt(obj.rate) and flt(obj.billed_amt)) else flt(obj.qty)
 
 	doc = get_mapped_doc("Purchase Order", source_name,	{
 		"Purchase Order": {
diff --git a/erpnext/selling/doctype/sales_order/sales_order.py b/erpnext/selling/doctype/sales_order/sales_order.py
index bffa581..498aec1 100644
--- a/erpnext/selling/doctype/sales_order/sales_order.py
+++ b/erpnext/selling/doctype/sales_order/sales_order.py
@@ -329,7 +329,7 @@
 	def update_item(source, target, source_parent):
 		target.amount = flt(source.amount) - flt(source.billed_amt)
 		target.base_amount = target.amount * flt(source_parent.conversion_rate)
-		target.qty = source.rate and target.amount / flt(source.rate) or source.qty
+		target.qty = target.amount / flt(source.rate) if (source.rate and source.billed_amt) else source.qty
 
 	doclist = get_mapped_doc("Sales Order", source_name, {
 		"Sales Order": {