diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index d56cd4e4aaf..a9d67f104ff 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -4160,7 +4160,7 @@ function dol_strlen($string, $stringencoding = 'UTF-8')
  * Make a substring. Works even if mbstring module is not enabled for better compatibility.
  *
  * @param	string		$string				String to scan
- * @param	string		$start				Start position
+ * @param	string		$start				Start position (0 for first char)
  * @param	int|null	$length				Length (in nb of characters or nb of bytes depending on trunconbytes param)
  * @param   string		$stringencoding		Page code used for input string encoding
  * @param	int			$trunconbytes		1=Length is max of bytes instead of max of characters