diff --git a/erpnext/selling/doctype/sales_order/test_sales_order.py b/erpnext/selling/doctype/sales_order/test_sales_order.py
index 2de0168812d..e971b4a53cd 100644
--- a/erpnext/selling/doctype/sales_order/test_sales_order.py
+++ b/erpnext/selling/doctype/sales_order/test_sales_order.py
@@ -2225,13 +2225,19 @@ def make_sales_order(**args):
 	return so
 
 
+<<<<<<< HEAD
 def create_dn_against_so(so, delivered_qty=0):
 	frappe.db.set_value("Stock Settings", None, "allow_negative_stock", 1)
+=======
+def create_dn_against_so(so, delivered_qty=0, do_not_submit=False):
+	frappe.db.set_single_value("Stock Settings", "allow_negative_stock", 1)
+>>>>>>> 4f396d3049 (test: SO reference validation)
 
 	dn = make_delivery_note(so)
 	dn.get("items")[0].qty = delivered_qty or 5
 	dn.insert()
-	dn.submit()
+	if not do_not_submit:
+		dn.submit()
 	return dn
 
 
diff --git a/erpnext/stock/doctype/delivery_note/test_delivery_note.py b/erpnext/stock/doctype/delivery_note/test_delivery_note.py
index 9f2c0be75d0..6e735ea67b7 100644
--- a/erpnext/stock/doctype/delivery_note/test_delivery_note.py
+++ b/erpnext/stock/doctype/delivery_note/test_delivery_note.py
@@ -723,6 +723,15 @@ class TestDeliveryNote(FrappeTestCase):
 		dn.cancel()
 		self.assertEqual(dn.status, "Cancelled")
 
+	def test_sales_order_reference_validation(self):
+		so = make_sales_order(po_no="12345")
+		dn = create_dn_against_so(so.name, delivered_qty=2, do_not_submit=True)
+		dn.items[0].against_sales_order = None
+		self.assertRaises(frappe.ValidationError, dn.save)
+		dn.reload()
+		dn.items[0].so_detail = None
+		self.assertRaises(frappe.ValidationError, dn.save)
+
 	def test_dn_billing_status_case1(self):
 		# SO -> DN -> SI
 		so = make_sales_order(po_no="12345")