diff --git a/erpnext/stock/doctype/material_request/material_request.py b/erpnext/stock/doctype/material_request/material_request.py
index 673b64a..ef5f24e 100644
--- a/erpnext/stock/doctype/material_request/material_request.py
+++ b/erpnext/stock/doctype/material_request/material_request.py
@@ -233,7 +233,7 @@
 				mr_obj.update_requested_qty(mr_item_rows)
 
 def set_missing_values(source, target_doc):
-	if getdate(target_doc.schedule_date) <  getdate(nowdate()):
+	if target_doc.doctype == "Purchase Order" and getdate(target_doc.schedule_date) <  getdate(nowdate()):
 		target_doc.schedule_date = None
 	target_doc.run_method("set_missing_values")
 	target_doc.run_method("calculate_taxes_and_totals")