diff --git a/htdocs/core/lib/ajax.lib.php b/htdocs/core/lib/ajax.lib.php
index 1fc5e23ebb4..1e6330ba35a 100644
--- a/htdocs/core/lib/ajax.lib.php
+++ b/htdocs/core/lib/ajax.lib.php
@@ -547,7 +547,7 @@ function ajax_constantonoff($code, $input=array(), $entity=null, $revertonoff=0,
  *  @param  string  $text_on    Text if on
  *  @param  string  $text_off   Text if off
  *  @param  array   $input      Array of type->list of CSS element to switch. Example: array('disabled'=>array(0=>'cssid'))
- *  @return void
+ *  @return string              html for button on/off
  */
 function ajax_object_onoff($object, $code, $field, $text_on, $text_off, $input=array())
 {