diff --git a/classes/AdminController.php b/classes/AdminController.php
index 4fac05414..a4a9142c1 100644
--- a/classes/AdminController.php
+++ b/classes/AdminController.php
@@ -364,7 +364,7 @@ class AdminControllerCore extends Controller
 		$this->addCSS(_PS_JS_DIR_.'jquery/datepicker/datepicker.css', 'all');
 		$this->addCSS(_PS_CSS_DIR_.'admin.css', 'all');
 		$this->addCSS(_PS_CSS_DIR_.'jquery.cluetip.css', 'all');
-		$this->addCSS(str_replace(_PS_ROOT_DIR_.'/', __PS_BASE_URI__, _PS_ADMIN_DIR_.'/').'themes/default/admin.css', 'all');
+		$this->addCSS(__PS_BASE_URI__.str_replace(_PS_ROOT_DIR_.DIRECTORY_SEPARATOR,'', _PS_ADMIN_DIR_).'/themes/default/admin.css', 'all');
 		if ($this->context->language->is_rtl)
 			$this->addCSS(_THEME_CSS_DIR_.'rtl.css');