diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index e3e76ad..f590613 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -612,7 +612,8 @@
  * specific pattern:
  * - $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
+ *   styles, or dynamically-resized images. The default pattern provided below
+ *   also excludes the private file system. If you need to add more paths, you
  *   can add '|path' to the expression.
  * - $conf['system.performance']['fast_404']['paths']: A regular expression to
  *   match paths that should return a simple 404 page, rather than the fully
@@ -623,7 +624,7 @@
  *
  * Remove the leading hash signs if you would like to alter this functionality.
  */
-# $config['system.performance']['fast_404']['exclude_paths'] = '/\/(?:styles)\//';
+# $config['system.performance']['fast_404']['exclude_paths'] = '/\/(?:styles)|(?:system\/files)\//';
 # $config['system.performance']['fast_404']['paths'] = '/\.(?:txt|png|gif|jpe?g|css|js|ico|swf|flv|cgi|bat|pl|dll|exe|asp)$/i';
 # $config['system.performance']['fast_404']['html'] = '<!DOCTYPE html><html><head><title>404 Not Found</title></head><body><h1>Not Found</h1><p>The requested URL "@path" was not found on this server.</p></body></html>';
 
