diff --git a/src/Omnipay/BarclaysEpdq/EssentialGateway.php b/src/Omnipay/BarclaysEpdq/EssentialGateway.php
index 2dddc76..54299de 100644
--- a/src/Omnipay/BarclaysEpdq/EssentialGateway.php
+++ b/src/Omnipay/BarclaysEpdq/EssentialGateway.php
@@ -23,7 +23,9 @@ public function getDefaultParameters()
             'clientId' => '',
             'testMode' => false,
             'language' => 'en_US',
-            'callbackMethod' => 'POST'
+            'callbackMethod' => 'POST',
+            'shaIn' => '',
+            'shaOut' => ''
         );
     }