diff --git a/erpnext/patches/v8_1/set_delivery_date_in_so_item.py b/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
index aa5cbc5..e3e23a5 100644
--- a/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
+++ b/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
@@ -13,11 +13,11 @@
 
 	frappe.db.sql("""
 		update `tabSales Order` so, `tabSales Order Item` so_item
-		set so_item.delivery_date = so.delivery_date
+		set so_item.delivery_date = if(ifnull(so.delivery_date, '0000-00-00'), ifnull(so.delivery_date, '0000-00-00'), '0000-00-00')
 		where so.name = so_item.parent
 			and so.order_type = 'Sales'
 			and (so_item.delivery_date is null or so_item.delivery_date = ''
 				or so_item.delivery_date = '0000-00-00')
-			and (so.delivery_date is not null and so.delivery_date != ''
+			and (so.delivery_date is not null and so.delivery_date != '' and so.delivery_date != ""
 				and so.delivery_date != '0000-00-00')
 	""")