diff --git a/core/lib/Drupal/Core/Form/FormCache.php b/core/lib/Drupal/Core/Form/FormCache.php
index 3371944..ba7cfd6 100644
--- a/core/lib/Drupal/Core/Form/FormCache.php
+++ b/core/lib/Drupal/Core/Form/FormCache.php
@@ -170,7 +170,9 @@ protected function loadCachedFormState($form_build_id, FormStateInterface $form_
         }
       }
       // Retrieve the list of previously known safe strings and store it for
-      // this request.
+      // this request. The safety of these strings has already been determined
+      // in setCache(). This insures that the strings being passed to this
+      // function have been marked as safe.
       // @todo Ensure we are not storing an excessively large string list
       //   in: https://www.drupal.org/node/2295823
       $build_info += ['safe_strings' => []];