diff --git a/core/lib/Drupal/Core/Access/CustomAccessCheck.php b/core/lib/Drupal/Core/Access/CustomAccessCheck.php
index 95b35e7..159d9d5 100644
--- a/core/lib/Drupal/Core/Access/CustomAccessCheck.php
+++ b/core/lib/Drupal/Core/Access/CustomAccessCheck.php
@@ -16,6 +16,10 @@
  *
  * You should only use it when you are sure that the access callback will not be
  * reused. Good examples in core are Edit or Toolbar module.
+ *
+ * The method is called on another instance of the controller class, so you
+ * cannot reuse any stored property of your actual controller instance used
+ * to generate the output.
  */
 class CustomAccessCheck implements StaticAccessCheckInterface {