diff --git a/core/lib/Drupal/Core/Form/FormCache.php b/core/lib/Drupal/Core/Form/FormCache.php
index ea38fd2..d7ed27e 100644
--- a/core/lib/Drupal/Core/Form/FormCache.php
+++ b/core/lib/Drupal/Core/Form/FormCache.php
@@ -26,6 +26,11 @@
 class FormCache implements FormCacheInterface {
 
   /**
+   * The default lifetime of the form's cache is set to 6 hours.
+   */
+  const CACHE_LIFETIME = 21600;
+
+  /**
    * The factory for expirable key value stores used by form cache.
    *
    * @var \Drupal\Core\KeyValueStore\KeyValueExpirableFactoryInterface
@@ -188,8 +193,7 @@ protected function loadCachedFormState($form_build_id, FormStateInterface $form_
    * {@inheritdoc}
    */
   public function setCache($form_build_id, $form, FormStateInterface $form_state) {
-    // 6 hours cache life time for forms should be plenty.
-    $expire = 21600;
+    $expire = static::CACHE_LIFETIME;
 
     // Ensure that the form build_id embedded in the form structure is the same
     // as the one passed in as a parameter. This is an additional safety measure