diff --git a/htdocs/core/actions_builddoc.inc.php b/htdocs/core/actions_builddoc.inc.php
index 63cac253976..7cde7e6f886 100644
--- a/htdocs/core/actions_builddoc.inc.php
+++ b/htdocs/core/actions_builddoc.inc.php
@@ -66,13 +66,13 @@ if ($action == 'builddoc' && $permissiontoadd) {
 		$outputlangs = $langs;
 		$newlang = '';
 
-		if ($conf->global->MAIN_MULTILANGS && empty($newlang) && GETPOST('lang_id', 'aZ09')) {
+		if (!empty($conf->global->MAIN_MULTILANGS) && empty($newlang) && GETPOST('lang_id', 'aZ09')) {
 			$newlang = GETPOST('lang_id', 'aZ09');
 		}
-		if ($conf->global->MAIN_MULTILANGS && empty($newlang) && isset($object->thirdparty->default_lang)) {
+		if (!empty($conf->global->MAIN_MULTILANGS) && empty($newlang) && isset($object->thirdparty->default_lang)) {
 			$newlang = $object->thirdparty->default_lang; // for proposal, order, invoice, ...
 		}
-		if ($conf->global->MAIN_MULTILANGS && empty($newlang) && isset($object->default_lang)) {
+		if (!empty($conf->global->MAIN_MULTILANGS) && empty($newlang) && isset($object->default_lang)) {
 			$newlang = $object->default_lang; // for thirdparty
 		}
 		if (!empty($newlang)) {