diff --git a/htdocs/core/ajax/fileupload.php b/htdocs/core/ajax/fileupload.php
index 379a2e689a3..4e05c7d8cb6 100644
--- a/htdocs/core/ajax/fileupload.php
+++ b/htdocs/core/ajax/fileupload.php
@@ -19,6 +19,8 @@
 /**
  *       \file       htdocs/core/ajax/fileupload.php
  *       \brief      File to return Ajax response on file upload
+ *
+ *       Option MAIN_USE_JQUERY_FILEUPLOAD must be enabled to have this feature working. Use is NOT secured !
  */
 
 if (!defined('NOTOKENRENEWAL')) {
diff --git a/htdocs/core/class/fileupload.class.php b/htdocs/core/class/fileupload.class.php
index 2c2ad868845..2cbbd7a3706 100644
--- a/htdocs/core/class/fileupload.class.php
+++ b/htdocs/core/class/fileupload.class.php
@@ -19,6 +19,8 @@
 /**
  *       \file       htdocs/core/class/fileupload.class.php
  *       \brief      File to return Ajax response on file upload
+ *
+ *       Option MAIN_USE_JQUERY_FILEUPLOAD must be enabled to have feature working. Use is NOT secured !
  */
 
 require_once DOL_DOCUMENT_ROOT.'/core/lib/files.lib.php';