diff --git a/eopayment/systempayv2.py b/eopayment/systempayv2.py
index 99f1cb4..6f6b869 100644
--- a/eopayment/systempayv2.py
+++ b/eopayment/systempayv2.py
@@ -244,6 +244,7 @@ class Payment(PaymentCommon):
 
     '''
     service_url = "https://paiement.systempay.fr/vads-payment/"
+    signature_algo = 'sha1'
 
     description = {
         'caption': 'SystemPay, système de paiment du groupe BPCE',
@@ -274,7 +275,7 @@ class Payment(PaymentCommon):
                 'validation': lambda value: str.isalnum(value), },
             {'name': 'signature_algo',
                 'caption': _(u'Algorithme de signature'),
-                'default': 'hmac_sha256',
+                'default': 'sha1',
                 'choices': (
                     ('sha1', 'SHA-1'),
                     ('hmac_sha256', 'HMAC-SHA-256'),