diff --git a/lib/main.html b/lib/main.html
index 5e5d13c3..15e2bbeb 100644
--- a/lib/main.html
+++ b/lib/main.html
@@ -77,6 +77,7 @@
   <script src="../node_modules/codemirror/addon/mode/overlay.js"></script>
   <script src="../node_modules/codemirror/addon/mode/loadmode.js"></script>
   <script src="../node_modules/codemirror/addon/mode/simple.js"></script>
+  <script src="../node_modules/codemirror/addon/mode/multiplex.js"></script>
   <script src="../node_modules/codemirror/keymap/sublime.js"></script>
   <script src="../node_modules/codemirror/keymap/vim.js"></script>
   <script src="../node_modules/codemirror/keymap/emacs.js"></script>