diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
index aaa3464..106d726 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
@@ -180,7 +180,7 @@ protected function variable_set($name, $value) {
    * Specialized refreshVariables().
    */
   protected function refreshVariables() {
-    // No operation if the child has not been upgraded yet.
+    // Refresh the variables only if the site was already upgraded.
     if ($this->upgradedSite) {
       global $conf;
       cache('bootstrap')->delete('variables');