diff --git a/install-dev/upgrade/php/upgrade_cms_15.php b/install-dev/upgrade/php/upgrade_cms_15.php
index 49efd29ee..ed407cfd3 100644
--- a/install-dev/upgrade/php/upgrade_cms_15.php
+++ b/install-dev/upgrade/php/upgrade_cms_15.php
@@ -1,11 +1,35 @@
 <?php
+
+/*
+* 2007-2012 PrestaShop
+*
+* NOTICE OF LICENSE
+*
+* This source file is subject to the Open Software License (OSL 3.0)
+* that is bundled with this package in the file LICENSE.txt.
+* It is also available through the world-wide-web at this URL:
+* http://opensource.org/licenses/osl-3.0.php
+* If you did not receive a copy of the license and are unable to
+* obtain it through the world-wide-web, please send an email
+* to license@prestashop.com so we can send you a copy immediately.
+*
+* DISCLAIMER
+*
+* Do not edit or add to this file if you wish to upgrade PrestaShop to newer
+* versions in the future. If you wish to customize PrestaShop for your
+* needs please refer to http://www.prestashop.com for more information.
+*
+*  @author PrestaShop SA <contact@prestashop.com>
+*  @copyright  2007-2012 PrestaShop SA
+*  @version  Release: $Revision$
+*  @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
+*  International Registered Trademark & Property of PrestaShop SA
+*/
 function upgrade_cms_15()
 {
 	$res = true;
-	$id_module_cms = Db::getInstance()->getValue('SELECT id_module from `'._DB_PREFIX_.'_module where name="blockcms"`');
-	if (!$id_module_cms)
-		return true;
 
+	// note : cms_shop table is required and independant of blockcms module
 	$res &= Db::getInstance()->execute('CREATE TABLE `'._DB_PREFIX_.'_cms_shop` (
 `id_cms` INT( 11 ) UNSIGNED NOT NULL,
 `id_shop` INT( 11 ) UNSIGNED NOT NULL ,
@@ -13,6 +37,11 @@ function upgrade_cms_15()
 	KEY `id_shop` (`id_shop`)
 ) ENGINE=ENGINE_TYPE  DEFAULT CHARSET=utf8;');
 	$res &= Db::getInstance()->execute('INSERT INTO `'._DB_PREFIX_.'_cms_shop` (id_shop, id_cms) (SELECT 1, id_cms FROM '._DB_PREFIX_.'_cms)');
+	
+	// cms_block table is blockcms module dependant. Don't update table that does not exists
+	$id_module_cms = Db::getInstance()->getValue('SELECT id_module from `'._DB_PREFIX_.'_module where name="blockcms"`');
+	if (!$id_module_cms)
+		return $res;
 	$res &= Db::getInstance()->execute('ALTER TABLE `'._DB_PREFIX_.'._cms_block` ADD `id_shop` INT(11) UNSIGNED NOT NULL DEFAULT "1" AFTER `id_cms_block`');
 
 	return $res;