diff --git a/templates/web/index.tt2.html b/templates/web/index.tt2.html
index 0cd093d3a9e9cb2cc772fd89a8baef12f4528699..2cfc0a80f7c6a8242f0c58fca75052d7c520351c 100644
--- a/templates/web/index.tt2.html
+++ b/templates/web/index.tt2.html
@@ -1,5 +1,5 @@
<!doctype html>
-<html lang="en">
+<html lang="[% lh.language_tag() %]">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>