diff --git a/erpnext/manufacturing/doctype/job_card/job_card.py b/erpnext/manufacturing/doctype/job_card/job_card.py
index fb26062..d764db3 100644
--- a/erpnext/manufacturing/doctype/job_card/job_card.py
+++ b/erpnext/manufacturing/doctype/job_card/job_card.py
@@ -433,7 +433,8 @@
 def make_stock_entry(source_name, target_doc=None):
 	def update_item(obj, target, source_parent):
 		target.t_warehouse = source_parent.wip_warehouse
-		target.conversion_factor = 1
+		if not target.conversion_factor:
+			target.conversion_factor = 1
 
 	def set_missing_values(source, target):
 		target.purpose = "Material Transfer for Manufacture"