diff --git a/sale.py b/sale.py
index 09ab1ab255..82c84d9025 100644
--- a/sale.py
+++ b/sale.py
@@ -37,9 +37,9 @@ class Sale:
                 )
         return invoice_domain
 
-    def _get_invoice_sale(self, invoice_type):
+    def _get_invoice_sale(self):
         Invoice = Pool().get('account.invoice')
-        invoice = super(Sale, self)._get_invoice_sale(invoice_type)
+        invoice = super(Sale, self)._get_invoice_sale()
         if self.invoice_grouping_method:
             domain = self._get_grouped_invoice_domain(invoice)
             order = self._get_grouped_invoice_order()
diff --git a/tests/scenario_sale_invoice_grouping.rst b/tests/scenario_sale_invoice_grouping.rst
index 74bb78b632..ee89562919 100644
--- a/tests/scenario_sale_invoice_grouping.rst
+++ b/tests/scenario_sale_invoice_grouping.rst
@@ -144,7 +144,7 @@ Check the invoices::
     2
     >>> invoice = invoices[0]
     >>> invoice.type
-    u'out_invoice'
+    u'out'
     >>> invoice.click('post')
     >>> invoice.state
     u'posted'