diff --git a/lib/Saml2/Response.php b/lib/Saml2/Response.php
index 519af8e0..de8bc168 100644
--- a/lib/Saml2/Response.php
+++ b/lib/Saml2/Response.php
@@ -795,7 +795,7 @@ private function _getAttributesByKeyName($keyName = "Name")
             if (in_array($attributeKeyName, array_keys($attributes), true)) {
                 if (!$allowRepeatAttributeName) {
                     throw new OneLogin_Saml2_ValidationError(
-                        "Found an Attribute element with duplicated ".$keyName,
+                        "Found an Attribute element with duplicated ".$keyName." (".$attributeKeyName.")" ,
                         OneLogin_Saml2_ValidationError::DUPLICATED_ATTRIBUTE_NAME_FOUND
                     );
                 }