diff --git a/modules/account_cash_rounding/purchase.py b/modules/account_cash_rounding/purchase.py
index 304e2c7f84..5b15b5eb59 100644
--- a/modules/account_cash_rounding/purchase.py
+++ b/modules/account_cash_rounding/purchase.py
@@ -72,7 +72,7 @@ class Purchase(metaclass=PoolMeta):
             amount = sum(map(self.currency.cash_round, amounts))
         return amount
 
-    def _get_invoice_purchase(self):
-        invoice = super()._get_invoice_purchase()
+    def _get_invoice(self):
+        invoice = super()._get_invoice()
         invoice.cash_rounding = self.cash_rounding
         return invoice
diff --git a/modules/purchase/purchase.py b/modules/purchase/purchase.py
index b4ef25aff2..88c664b483 100644
--- a/modules/purchase/purchase.py
+++ b/modules/purchase/purchase.py
@@ -813,7 +813,7 @@ class Purchase(
             purchase.total_amount_cache = purchase.total_amount
         cls.save(purchases)
 
-    def _get_invoice_purchase(self):
+    def _get_invoice(self):
         'Return invoice'
         pool = Pool()
         Invoice = pool.get('account.invoice')
@@ -844,7 +844,7 @@ class Purchase(
         if not invoice_lines:
             return
 
-        invoice = self._get_invoice_purchase()
+        invoice = self._get_invoice()
         if getattr(invoice, 'lines', None):
             invoice_lines = list(invoice.lines) + invoice_lines
         invoice.lines = invoice_lines