diff --git a/app/inc/i18n.php b/app/inc/i18n.php
index c2ddd1c1912e1e66bc4a7878bfbc8f8f2fda2f99..14a28cb7f6badd2fb627c5b3613994f65dde0b6e 100644
--- a/app/inc/i18n.php
+++ b/app/inc/i18n.php
@@ -29,7 +29,7 @@ if (isset($_POST['lang']) && is_string($_POST['lang']) && in_array($_POST['lang'
/* <html lang="$locale"> */
$i18n->get('', 'Something, just to load the dictionary');
-$locale = $i18n->getLoadedLang();
+$locale = str_replace('_', '-', $i18n->getLoadedLang());
/* Date Format */
$date_format['txt_full'] = __('Date', 'FULL'); //summary in create_date_poll.php and removal date in choix_(date|autre).php