--- a/docs/_templates/layout.html
+++ b/docs/_templates/layout.html
@@ -10,6 +10,7 @@
     {%- if builder != 'htmlhelp' %}
     <script type="text/javascript">
       var DOCUMENTATION_OPTIONS = {
+        HAS_SOURCE: true,
         URL_ROOT:   '{{ pathto("", 1) }}',
         VERSION:    '{{ release }}'
       };
