diff --git a/admin_manual/configuration_server/config_sample_php_parameters.rst b/admin_manual/configuration_server/config_sample_php_parameters.rst
index 9427333e8..0c78bfa45 100644
--- a/admin_manual/configuration_server/config_sample_php_parameters.rst
+++ b/admin_manual/configuration_server/config_sample_php_parameters.rst
@@ -1264,6 +1264,9 @@ lose this string there will be data corruption.
 
 List of trusted proxy servers
 
+If you configure these also consider setting `forwarded_for_headers` which
+otherwise defaults to `HTTP_X_FORWARDED_FOR` (the `X-Forwarded-For` header).
+
 ::
 
 	'forwarded_for_headers' => array('HTTP_X_FORWARDED', 'HTTP_FORWARDED_FOR'),