diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 3bea2419718..02f6eb57188 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -293,7 +293,7 @@ class SaleOrder(models.Model):
         """
         Create the invoice associated to the SO.
         :param grouped: if True, invoices are grouped by SO id. If False, invoices are grouped by
-                        (partner, currency)
+                        (partner_invoice_id, currency)
         :param final: if True, refunds will be generated if necessary
         :returns: list of created invoices
         """
@@ -302,7 +302,7 @@ class SaleOrder(models.Model):
         invoices = {}
 
         for order in self:
-            group_key = order.id if grouped else (order.partner_id.id, order.currency_id.id)
+            group_key = order.id if grouped else (order.partner_invoice_id.id, order.currency_id.id)
             for line in order.order_line.sorted(key=lambda l: l.qty_to_invoice < 0):
                 if float_is_zero(line.qty_to_invoice, precision_digits=precision):
                     continue