diff --git a/_includes/sidebar.html b/_includes/sidebar.html
index 586f47b2d74..cfe161d72dc 100644
--- a/_includes/sidebar.html
+++ b/_includes/sidebar.html
@@ -1,4 +1,4 @@
-<div class="sidebar">
+<header role="banner" class="sidebar">
   <div class="container sidebar-sticky">
     <div class="sidebar-about">
       <h1>
@@ -33,4 +33,4 @@ <h1>
 
     <p>&copy; {{ site.time | date: '%Y' }}. All rights reserved.</p>
   </div>
-</div>
+</header>
diff --git a/_layouts/default.html b/_layouts/default.html
index c99f6e636a2..8bee6263753 100644
--- a/_layouts/default.html
+++ b/_layouts/default.html
@@ -7,7 +7,7 @@
 
     {% include sidebar.html %}
 
-    <div class="content container">
+    <main role="main" class="content container">
       {{ content }}
     </div>