diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 67fe10c..121d91e 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -360,8 +360,10 @@ function system_requirements($phase) {
 
     // Set summary and description based on values determined above.
     $summary = t('Last run !time ago', array('!time' => \Drupal::service('date.formatter')->formatTimeDiffSince($cron_last)));
-    $description_string = '';
+    // Build the string and replacement arguments to be sent later to
+    // \Drupal\Component\Utility\SafeMarkup::format().
     $description_replacements = [];
+    $description_string = '';
     if ($severity != REQUIREMENT_INFO) {
       $description_warning = t('Cron has not run recently.');
       $description_replacements += [
@@ -373,11 +375,11 @@ function system_requirements($phase) {
 
     $description_manual = t('You can <a href="@cron">run cron manually</a>.', array('@cron' => \Drupal::url('system.run_cron')));
     $description_additional_info = t('To run cron from outside the site, go to <a href="@cron">@cron</a>', array('@cron' => \Drupal::url('system.cron', array('key' => \Drupal::state()->get('system.cron_key'), array('absolute' => TRUE)))));
-    $description_string .= '@description_manual<br />@description_additional_info';
     $description_replacements += [
       '@description_manual' => $description_manual,
       '@description_additional_info' => $description_additional_info,
     ];
+    $description_string .= '@description_manual<br />@description_additional_info';
     $description = SafeMarkup::format($description_string, $description_replacements);
 
     $requirements['cron'] = array(