diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index 9ad5cae..32eec6c 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -613,7 +613,9 @@
  * - $conf['system.performance]['fast_404']['exclude_paths']: A regular
  *   expression to match paths to exclude, such as images generated by image
  *   styles, or dynamically-resized images. If you need to add more paths, you
- *   can add '|path' to the expression.
+ *   can add '|path' to the expression. If you use private file download method
+ *   and expect images to display inline, you will have to add
+ *   "|(?:system\/files)" to the excluded paths.
  * - $conf['system.performance]['fast_404']['paths']: A regular expression to
  *   match paths that should return a simple 404 page, rather than the fully
  *   themed 404 page. If you don't have any aliases ending in htm or html you