diff --git a/htdocs/main.inc.php b/htdocs/main.inc.php
index 23e364f4b41..336693349e6 100644
--- a/htdocs/main.inc.php
+++ b/htdocs/main.inc.php
@@ -107,7 +107,7 @@ $langs->load("main");
  */
 if (defined("MAIN_NOT_INSTALLED"))
 {
-  Header("Location: install/index.php");
+  Header("Location: ".$dolibarr_main_url_root."/install/index.php");
 }