diff --git a/nengo_sphinx_theme/theme/layout.html b/nengo_sphinx_theme/theme/layout.html
index 05d0f92..f9a95d3 100644
--- a/nengo_sphinx_theme/theme/layout.html
+++ b/nengo_sphinx_theme/theme/layout.html
@@ -68,7 +68,7 @@
       <div class="col-12 col-md-8 col-xl-9">
         <div class="container">
           <div class="row">
-            <div class="col-10 offset-1 pb-5 documentation-source">
+            <div class="col-10 offset-1 pb-5 documentation-source" role="main">
               {% block body %} {% endblock %}
             </div>
           </div>