diff --git a/modules/admin/lib/FederationController.php b/modules/admin/lib/FederationController.php
index c031c68bfbf55c49399abd98a980295f2c55e4fa..cea4f480a6798aa364e36fd7da842f26deb9d195 100644
--- a/modules/admin/lib/FederationController.php
+++ b/modules/admin/lib/FederationController.php
@@ -479,6 +479,7 @@ class FederationController
             $mdconfig = $this->mdHandler->getMetaDataConfig($entityID, $set);
         }
 
+        /** @var array $certInfo  Second param ensures non-nullable return-value */
         $certInfo = Utils\Crypto::loadPublicKey($mdconfig, true, $prefix);
 
         $response = new Response($certInfo['PEM']);