diff --git a/lib/gollum/frontend/public/gollum/livepreview/js/livepreview.js b/lib/gollum/frontend/public/gollum/livepreview/js/livepreview.js
index 62cdbf25..7f82463e 100644
--- a/lib/gollum/frontend/public/gollum/livepreview/js/livepreview.js
+++ b/lib/gollum/frontend/public/gollum/livepreview/js/livepreview.js
@@ -246,6 +246,8 @@ function highlight( element, language ) {
 
 // Pygments and Ace have different names for languages.
 function pygmentsLanguageToAceMode( declaredLanguage ) {
+  declaredLanguage = declaredLanguage.toLowerCase();
+
   switch ( declaredLanguage ) {
     case 'c':
     case 'c++':