diff --git a/_includes/header.html b/_includes/header.html
index 6800799..c4de42e 100644
--- a/_includes/header.html
+++ b/_includes/header.html
@@ -23,7 +23,7 @@
 {% endif %}
 
 <!doctype html>
-<html class="min-height-full">
+<html class="min-height-full" lang="en-US">
   <head>
     <meta charset="utf-8">
     <title>{{ page_title }}</title>