diff --git a/www/saml2/idp/metadata.php b/www/saml2/idp/metadata.php
index 27f16507acfc911b398db28d3249291563749339..937d73a653ac4fc46a206595db8691605e343859 100644
--- a/www/saml2/idp/metadata.php
+++ b/www/saml2/idp/metadata.php
@@ -70,7 +70,7 @@ try {
 </EntityDescriptor>';
 	
 	
-	if ($_GET['output'] == 'xml') {
+	if (array_key_exists('output', $_GET) && $_GET['output'] == 'xml') {
 		header('Content-Type: application/xml');
 		
 		echo $metaxml;