diff --git a/modules/saml/lib/IdP/SAML2.php b/modules/saml/lib/IdP/SAML2.php
index cfbb5476d66e4256833cd9a47a1ae84d1f792109..104cdfcd3be2a057c7b46ed4887bb7dce4422979 100644
--- a/modules/saml/lib/IdP/SAML2.php
+++ b/modules/saml/lib/IdP/SAML2.php
@@ -1004,9 +1004,9 @@ class SAML2
 
         if ($nameIdFormat === null || !isset($state['saml:NameID'][$nameIdFormat])) {
             // either not set in request, or not set to a format we supply. Fall back to old generation method
-            $nameIdFormat = current($spMetadata->getArrayizeString('NameIDFormat', null));
+            $nameIdFormat = current($spMetadata->getArrayizeString('NameIDFormat', []));
             if ($nameIdFormat === null) {
-                $nameIdFormat = current($idpMetadata->getArrayizeString('NameIDFormat', \SAML2\Constants::NAMEID_TRANSIENT));
+                $nameIdFormat = current($idpMetadata->getArrayizeString('NameIDFormat', [\SAML2\Constants::NAMEID_TRANSIENT]));
             }
         }