diff --git a/htdocs/includes/modules/societe/modules_societe.class.php b/htdocs/includes/modules/societe/modules_societe.class.php
index 8dcbf1cb601..e0bff551f1d 100644
--- a/htdocs/includes/modules/societe/modules_societe.class.php
+++ b/htdocs/includes/modules/societe/modules_societe.class.php
@@ -2,7 +2,7 @@
 /* Copyright (C) 2003-2005 Rodolphe Quiedeville <rodolphe@quiedeville.org>
  * Copyright (C) 2004-2007 Laurent Destailleur  <eldy@users.sourceforge.net>
  * Copyright (C) 2004      Eric Seigne          <eric.seigne@ryxeo.com>
- * Copyright (C) 2005      Regis Houssin        <regis@dolibarr.fr>
+ * Copyright (C) 2005-2007 Regis Houssin        <regis@dolibarr.fr>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
diff --git a/htdocs/soc.php b/htdocs/soc.php
index 47cba816d43..4a29340414d 100644
--- a/htdocs/soc.php
+++ b/htdocs/soc.php
@@ -688,7 +688,7 @@ elseif ($_GET["action"] == 'edit' || $_POST["action"] == 'edit')
 
         print '<tr><td>'.$langs->trans("Prefix").'</td><td colspan="3">';
         // On ne permet pas la modification du préfix en mode de numérotation auto utilisant le prefix
-        if ($prefixCustomerIsUsed || $prefixSupplierIsUsed)
+        if (($prefixCustomerIsUsed || $prefixSupplierIsUsed) && $soc->prefix_comm)
         {
         	print '<input type="hidden" name="prefix_comm" value="'.$soc->prefix_comm.'">';
         	print $soc->prefix_comm;