diff --git a/htdocs/install/etape1.php b/htdocs/install/etape1.php
index c9713870c22..1365e7102eb 100644
--- a/htdocs/install/etape1.php
+++ b/htdocs/install/etape1.php
@@ -23,7 +23,7 @@
  *		\file       htdocs/install/etape1.php
  *		\ingroup	install
  *		\brief      Build conf file on disk
- *		\version    $Id: etape1.php,v 1.136 2011/07/31 23:26:18 eldy Exp $
+ *		\version    $Id: etape1.php,v 1.137 2011/08/04 13:19:26 eldy Exp $
  */
 
 define('DONOTLOADCONF',1);	// To avoid loading conf by file inc.php
@@ -64,14 +64,14 @@ $error = 0;
 // Repertoire des pages dolibarr
 $main_dir=isset($_POST["main_dir"])?trim($_POST["main_dir"]):'';
 
-// On supprime /  de fin dans main_dir
+// Remove last / into dans main_dir
 if (substr($main_dir, dol_strlen($main_dir) -1) == "/")
 {
 	$main_dir = substr($main_dir, 0, dol_strlen($main_dir)-1);
 }
 
-// On supprime /  de fin dans main_url
-if (substr($_POST["main_url"], dol_strlen($_POST["main_url"]) -1) == "/")
+// Remove last / into dans main_url
+if (! empty($_POST["main_url"]) && substr($_POST["main_url"], dol_strlen($_POST["main_url"]) -1) == "/")
 {
 	$_POST["main_url"] = substr($_POST["main_url"], 0, dol_strlen($_POST["main_url"])-1);
 }