diff --git a/eopayment/sips2.py b/eopayment/sips2.py
index 6e319e9..d01b849 100644
--- a/eopayment/sips2.py
+++ b/eopayment/sips2.py
@@ -50,6 +50,8 @@ class Payment(PaymentCommon):
         Worldline Benelux_Sips_Technical_integration_guide_Version_1.5.pdf
 
     '''
+    has_free_transaction_id = True
+
     URL = {
         'test': 'https://payment-webinit.simu.sips-atos.com/paymentInit',
         'prod': 'https://payment-webinit.sips-atos.com/paymentInit',