diff --git a/core/modules/system/src/Tests/Update/UpdatePathTestBase.php b/core/modules/system/src/Tests/Update/UpdatePathTestBase.php
index f3e3c29..fbb6dee 100644
--- a/core/modules/system/src/Tests/Update/UpdatePathTestBase.php
+++ b/core/modules/system/src/Tests/Update/UpdatePathTestBase.php
@@ -264,7 +264,8 @@ protected function runUpdates() {
    */
   protected function replaceUser1() {
     /** @var \Drupal\user\UserInterface $account */
-    // @todo: do this without saving the user account.
+    // @todo: Saving the account before the update is problematic.
+    //   https://www.drupal.org/node/2560237
     $account = User::load(1);
     $account->setPassword($this->rootUser->pass_raw);
     $account->setEmail($this->rootUser->getEmail());