diff --git a/erpnext/controllers/buying_controller.py b/erpnext/controllers/buying_controller.py
index 7fd8febd4f7..5ccf29d5033 100644
--- a/erpnext/controllers/buying_controller.py
+++ b/erpnext/controllers/buying_controller.py
@@ -112,8 +112,8 @@ class BuyingController(StockController):
 					valuation_amount_adjustment -= item.item_tax_amount
 
 				self.round_floats_in(item)
-
-				item.conversion_factor = get_conversion_factor(item.item_code, item.uom).get("conversion_factor") or 1.0
+				if flt(item.conversion_factor)==0:
+					item.conversion_factor = get_conversion_factor(item.item_code, item.uom).get("conversion_factor") or 1.0
 
 				qty_in_stock_uom = flt(item.qty * item.conversion_factor)
 				rm_supp_cost = flt(item.rm_supp_cost) if self.doctype=="Purchase Receipt" else 0.0