diff --git a/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php b/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php
index 99abd89..f664b09 100644
--- a/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php
+++ b/core/lib/Drupal/Core/Plugin/DefaultPluginManager.php
@@ -154,7 +154,8 @@ public function setCacheBackend(CacheBackendInterface $cache_backend, LanguageMa
    * Initializes the alter hook.
    *
    * @param string $alter_hook
-   *   Name of the alter hook.
+   *   Name of the alter hook; for example, to invoke
+   *   hook_mymodule_data_alter() pass in "mymodula_data".
    */
   protected function alterInfo($alter_hook) {
     $this->alterHook = $alter_hook;