diff --git a/install-dev/model.php b/install-dev/model.php
index 588c82693..f95eafba0 100644
--- a/install-dev/model.php
+++ b/install-dev/model.php
@@ -74,6 +74,7 @@ define('INSTALLER__PS_BASE_URI_ABSOLUTE', 'http://'.ToolsInstall::getHttpHost(fa
 // XML Header
 header('Content-Type: text/xml');
 
+define('_PS_ROOT_DIR_', realpath(INSTALL_PATH.'/../'));
 // Switching method
 if (isset($_GET['method']))
 {
diff --git a/install-dev/xml/checkConfig.php b/install-dev/xml/checkConfig.php
index dcecb7dff..2e0aec3f1 100644
--- a/install-dev/xml/checkConfig.php
+++ b/install-dev/xml/checkConfig.php
@@ -39,18 +39,18 @@ $tests = array(
 	'system' => $funcs,
 	'gd' => false,
 	'mysql_support' => false,
-	'config_dir' => INSTALL_PATH.'/../config/',
-	'cache_dir' => INSTALL_PATH.'/../cache/',
-	'sitemap' => INSTALL_PATH.'/../sitemap.xml',
-	'log_dir' => INSTALL_PATH.'/../log/',
-	'img_dir' => INSTALL_PATH.'/../img/',
-	'mails_dir' => INSTALL_PATH.'/../mails/',
-	'module_dir' => INSTALL_PATH.'/../modules/',
-	'theme_lang_dir' => INSTALL_PATH.'/../themes/prestashop/lang/',
-	'theme_cache_dir' => INSTALL_PATH.'/../themes/prestashop/cache/',
-	'translations_dir' => INSTALL_PATH.'/../translations/',
-	'customizable_products_dir' => INSTALL_PATH.'/../upload/',
-	'virtual_products_dir' => INSTALL_PATH.'/../download/',
+	'config_dir' => 'config',
+	'cache_dir' => 'cache',
+	'sitemap' => 'sitemap.xml',
+	'log_dir' => 'log',
+	'img_dir' => 'img',
+	'mails_dir' => 'mails/',
+	'module_dir' => 'modules/',
+	'theme_lang_dir' => 'themes/prestashop/lang',
+	'theme_cache_dir' => 'themes/prestashop/cache',
+	'translations_dir' => 'translations',
+	'customizable_products_dir' => 'upload',
+	'virtual_products_dir' => 'download',
 );
 $tests_op = array(
 	'fopen' => false,