diff --git a/addons/account_payment/controllers/portal.py b/addons/account_payment/controllers/portal.py
index df0aae049e1..3903fbfb4b3 100644
--- a/addons/account_payment/controllers/portal.py
+++ b/addons/account_payment/controllers/portal.py
@@ -20,7 +20,7 @@ class PortalAccount(portal.PortalAccount):
 
         # Make sure that the partner's company matches the invoice's company.
         invoice_company = invoice.company_id or request.env.company
-        PaymentPortal.ensure_matching_companies(partner, invoice_company)
+        PaymentPortal._ensure_matching_companies(partner, invoice_company)
 
         acquirers_sudo = request.env['payment.acquirer'].sudo()._get_compatible_acquirers(
             invoice_company.id, partner.id, currency_id=invoice.currency_id.id
diff --git a/addons/payment/controllers/portal.py b/addons/payment/controllers/portal.py
index c2b156414a9..ab6b9dcfd04 100644
--- a/addons/payment/controllers/portal.py
+++ b/addons/payment/controllers/portal.py
@@ -68,9 +68,9 @@ class PaymentPortal(portal.CustomerPortal):
         """
         # Cast numeric parameters as int or float and void them if their str value is malformed
         currency_id, acquirer_id, partner_id, company_id, invoice_id = tuple(map(
-            self.cast_as_int, (currency_id, acquirer_id, partner_id, company_id, invoice_id)
+            self._cast_as_int, (currency_id, acquirer_id, partner_id, company_id, invoice_id)
         ))
-        amount = self.cast_as_float(amount)
+        amount = self._cast_as_float(amount)
 
         # Raise an HTTP 404 if a partner is provided with an invalid access token
         if partner_id:
@@ -104,7 +104,7 @@ class PaymentPortal(portal.CustomerPortal):
         currency_id = currency_id or company.currency_id.id
 
         # Make sure that the company passed as parameter matches the partner's company.
-        PaymentPortal.ensure_matching_companies(partner_sudo, company)
+        PaymentPortal._ensure_matching_companies(partner_sudo, company)
 
         # Make sure that the currency exists and is active
         currency = request.env['res.currency'].browse(currency_id).exists()
@@ -346,7 +346,7 @@ class PaymentPortal(portal.CustomerPortal):
         :param dict kwargs: Optional data. This parameter is not used here
         :raise: werkzeug.exceptions.NotFound if the access token is invalid
         """
-        tx_id = self.cast_as_int(tx_id)
+        tx_id = self._cast_as_int(tx_id)
         if tx_id:
             tx_sudo = request.env['payment.transaction'].sudo().browse(tx_id)
 
@@ -404,7 +404,7 @@ class PaymentPortal(portal.CustomerPortal):
             token_sudo.active = False
 
     @staticmethod
-    def cast_as_int(str_value):
+    def _cast_as_int(str_value):
         """ Cast a string as an `int` and return it.
 
         If the conversion fails, `None` is returned instead.
@@ -419,7 +419,7 @@ class PaymentPortal(portal.CustomerPortal):
             return None
 
     @staticmethod
-    def cast_as_float(str_value):
+    def _cast_as_float(str_value):
         """ Cast a string as a `float` and return it.
 
         If the conversion fails, `None` is returned instead.
@@ -434,7 +434,7 @@ class PaymentPortal(portal.CustomerPortal):
             return None
 
     @staticmethod
-    def ensure_matching_companies(partner, document_company):
+    def _ensure_matching_companies(partner, document_company):
         """ Check that the partner's company is the same as the document's company.
 
         If the partner company is not set, the check passes. If the companies don't match, a
diff --git a/addons/sale/controllers/portal.py b/addons/sale/controllers/portal.py
index 92b38d3067f..41c68bf65f2 100644
--- a/addons/sale/controllers/portal.py
+++ b/addons/sale/controllers/portal.py
@@ -154,7 +154,7 @@ class CustomerPortal(portal.CustomerPortal):
             logged_in = not request.env.user._is_public()
 
             # Make sure that the partner's company matches the sales order's company.
-            payment_portal.PaymentPortal.ensure_matching_companies(
+            payment_portal.PaymentPortal._ensure_matching_companies(
                 order_sudo.partner_id, order_sudo.company_id
             )
 
@@ -321,8 +321,8 @@ class PaymentPortal(payment_portal.PaymentPortal):
         :raise: ValidationError if the order id is invalid
         """
         # Cast numeric parameters as int or float and void them if their str value is malformed
-        amount = self.cast_as_float(amount)
-        sale_order_id = self.cast_as_int(sale_order_id)
+        amount = self._cast_as_float(amount)
+        sale_order_id = self._cast_as_int(sale_order_id)
         if sale_order_id:
             order_sudo = request.env['sale.order'].sudo().browse(sale_order_id).exists()
             if not order_sudo: