diff --git a/addons/point_of_sale/point_of_sale.py b/addons/point_of_sale/point_of_sale.py
index cf152131f99..e8747465eb9 100644
--- a/addons/point_of_sale/point_of_sale.py
+++ b/addons/point_of_sale/point_of_sale.py
@@ -396,7 +396,7 @@ class pos_order(osv.osv):
             'name': _('Customer Invoice'),
             'view_type': 'form',
             'view_mode': 'form',
-            'view_id': res_id,
+            'view_id': [res_id],
             'res_model': 'account.invoice',
             'context': "{'type':'out_invoice'}",
             'type': 'ir.actions.act_window',