diff --git a/mocha.css b/mocha.css
index f96b310cc5..01bac1abc1 100644
--- a/mocha.css
+++ b/mocha.css
@@ -1,4 +1,4 @@
-
+@charset "UTF-8";
 body {
   font: 20px/1.5 "Helvetica Neue", Helvetica, Arial, sans-serif;
   padding: 60px 50px;