diff --git a/lib/SimpleSAML/Utils/HTTP.php b/lib/SimpleSAML/Utils/HTTP.php
index 3e9d0585076bd5c2ac2184aff6da7b4ec2744c7b..0bd1e351f6f38a56a9a8d9f1a4b95789830cbb59 100644
--- a/lib/SimpleSAML/Utils/HTTP.php
+++ b/lib/SimpleSAML/Utils/HTTP.php
@@ -375,7 +375,7 @@ class HTTP
 
         // get the white list of domains
         if ($trustedSites === null) {
-            $trustedSites = Configuration::getInstance()->getValue('trusted.url.domains', []);
+            $trustedSites = Configuration::getInstance()->getOptionalArray('trusted.url.domains', []);
         }
 
         // validates the URL's host is among those allowed