diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index d37b33f9540..37b2830c084 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -831,11 +831,19 @@ def get_mapped_purchase_invoice(source_name, target_doc=None, ignore_permissions
 		target.credit_to = get_party_account("Supplier", source.supplier, source.company)
 
 	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) and flt(obj.billed_amt)) else flt(obj.qty)
-		)
+		def get_billed_qty(po_item_name):
+			from frappe.query_builder.functions import Sum
+
+			table = frappe.qb.DocType("Purchase Invoice Item")
+			query = (
+				frappe.qb.from_(table)
+				.select(Sum(table.qty).as_("qty"))
+				.where((table.docstatus == 1) & (table.po_detail == po_item_name))
+			)
+			return query.run(pluck="qty")[0] or 0
+
+		billed_qty = flt(get_billed_qty(obj.name))
+		target.qty = flt(obj.qty) - billed_qty
 
 		item = get_item_defaults(target.item_code, source_parent.company)
 		item_group = get_item_group_defaults(target.item_code, source_parent.company)