diff --git a/sermepa/sermepa_test.py b/sermepa/sermepa_test.py
index 3172e8a..c97e862 100755
--- a/sermepa/sermepa_test.py
+++ b/sermepa/sermepa_test.py
@@ -179,7 +179,7 @@ def test_sendingPost_testing(self):
             Ds_Merchant_MerchantData = "COBRAMENT QUOTA SOCI",
             Ds_Merchant_MerchantName = "SOM ENERGIA, SCCL",
             Ds_Merchant_MerchantURL = "https://testing.somenergia.coop:5001/pagament/notificacio",
-            Ds_Merchant_Order = "20167db2f375",
+            Ds_Merchant_Order = randhex(nbytes=6), # "20167db2f375",
             Ds_Merchant_ProductDescription = "Alta de soci SOMENERGIA",
             Ds_Merchant_SumTotal = "10000",
             Ds_Merchant_Terminal = "1",
@@ -210,7 +210,7 @@ def test_sendingPost_testing_invalidSignature(self):
             Ds_Merchant_MerchantData = "COBRAMENT QUOTA SOCI",
             Ds_Merchant_MerchantName = "SOM ENERGIA, SCCL",
             Ds_Merchant_MerchantURL = "https://testing.somenergia.coop:5001/pagament/notificacio",
-            Ds_Merchant_Order = "20167db2f375",
+            Ds_Merchant_Order = randhex(nbytes=6), # "20167db2f375",
             Ds_Merchant_ProductDescription = "Alta de soci SOMENERGIA",
             Ds_Merchant_SumTotal = "10000",
             Ds_Merchant_Terminal = "1",