diff --git a/app/models/sale.rb b/app/models/sale.rb
index a214c551..677dabe4 100644
--- a/app/models/sale.rb
+++ b/app/models/sale.rb
@@ -47,7 +47,7 @@ class Sale < ApplicationRecord
     end
   end
 
-  def generate_invoice_from_order (order_id, sale_id, booking, requested_by, cashier)
+  def generate_invoice_from_order (order_id, sale_id, booking, requested_by, cashier = nil)
     taxable = true
     #if sale_id is exsit and validate
     #add order to that invoice