diff --git a/web/index.html b/web/index.html
index 70ba49c..6926a20 100644
--- a/web/index.html
+++ b/web/index.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html>
+<html lang="de">
 <head>
   <!--
     If you are serving your web app in a path other than the root, change the
