diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 19b39fd776d..a25fd098f9a 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -5274,10 +5274,10 @@ function get_exdir($num, $level, $alpha, $withoutslash, $object, $modulepart)
 /**
  *	Creation of a directory (this can create recursive subdir)
  *
- *	@param	string	$dir		Directory to create (Separator must be '/'. Example: '/mydir/mysubdir')
- *	@param	string	$dataroot	Data root directory (To avoid having the data root in the loop. Using this will also lost the warning on first dir PHP has no permission when open_basedir is used)
- *  @param	int		$newmask	Mask for new file (Defaults to $conf->global->MAIN_UMASK or 0755 if unavailable). Example: '0444'
- *	@return int         		< 0 if KO, 0 = already exists, > 0 if OK
+ *	@param	string		$dir		Directory to create (Separator must be '/'. Example: '/mydir/mysubdir')
+ *	@param	string		$dataroot	Data root directory (To avoid having the data root in the loop. Using this will also lost the warning on first dir PHP has no permission when open_basedir is used)
+ *  @param	string|null	$newmask	Mask for new file (Defaults to $conf->global->MAIN_UMASK or 0755 if unavailable). Example: '0444'
+ *	@return int         			< 0 if KO, 0 = already exists, > 0 if OK
  */
 function dol_mkdir($dir, $dataroot = '', $newmask = null)
 {