diff --git a/addons/payment/models/payment_transaction.py b/addons/payment/models/payment_transaction.py
index 47df8f02493..4453a13b464 100644
--- a/addons/payment/models/payment_transaction.py
+++ b/addons/payment/models/payment_transaction.py
@@ -311,7 +311,7 @@ class PaymentTransaction(models.Model):
             raise ValidationError(_("Only confirmed transactions can be refunded."))
 
         for tx in self:
-            tx._send_refund_request(amount_to_refund)
+            tx._send_refund_request(amount_to_refund=amount_to_refund)
 
     #=== BUSINESS METHODS - PAYMENT FLOW ===#