diff --git a/public/js/mathjax-config-extra.js b/public/js/mathjax-config-extra.js
index 54cee79..11ba59c 100644
--- a/public/js/mathjax-config-extra.js
+++ b/public/js/mathjax-config-extra.js
@@ -1,4 +1,4 @@
-var MathJax = {
+window.MathJax = {
   messageStyle: 'none',
   skipStartupTypeset: true,
   tex2jax: {