diff --git a/src/Message/Response/AbstractRabobankResponse.php b/src/Message/Response/AbstractRabobankResponse.php
index <HASH>..<HASH> 100644
--- a/src/Message/Response/AbstractRabobankResponse.php
+++ b/src/Message/Response/AbstractRabobankResponse.php
@@ -43,9 +43,10 @@ class AbstractRabobankResponse extends AbstractResponse
         if (!isset($this->data['signature'])) {
             return;
         }
-
-        $signatureData = $this->data;
-        unset($signatureData['signature']);
+        
+        $signatureData = [
+            'redirectUrl' => $this->data['redirectUrl'] ?? '',
+        ];
 
         $signature = $this->request->gateway->generateSignature($this->flattenData($signatureData));
Update AbstractRabobankResponse.php

Changed the building of the signatureData array. Since only the redirectURl is needed to validate the purchase response url we should make  sure  its the only thing in the array.