diff --git a/lib/SimpleSAML/Utils/Config/Metadata.php b/lib/SimpleSAML/Utils/Config/Metadata.php
index caf7b4a8775b5e571b6f83453cebad952883aec5..632ec04cca8156bb31e1c7ee0ea452a48466d30e 100644
--- a/lib/SimpleSAML/Utils/Config/Metadata.php
+++ b/lib/SimpleSAML/Utils/Config/Metadata.php
@@ -230,7 +230,7 @@ class Metadata
                 continue;
             }
 
-            if (array_key_exists('isDefault', $ep)) {
+            if (isset($ep['isDefault'])) {
                 if ($ep['isDefault'] === true) {
                     // this is the first endpoint with isDefault set to true
                     return $ep;