diff --git a/assets/index.ja-ryu.html b/assets/index.ja-ryu.html
index bdf45da..b8384b1 100644
--- a/assets/index.ja-ryu.html
+++ b/assets/index.ja-ryu.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html> 
-<html lang="ja">
+<html lang="ja-ryu">
   <!-- This file was automatically generated by webgen/gen.rb. Do not make changes to this file manually. -->
   <head>
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
