diff --git a/source/index.html.md b/source/index.html.md
index 8fd3b20..3c0f8f9 100644
--- a/source/index.html.md
+++ b/source/index.html.md
@@ -1,7 +1,7 @@
 ---
 title: API Reference
 
-language_tabs:
+language_tabs: # must be one of https://git.io/vQNgJ
   - shell
   - ruby
   - python