diff --git a/lib/core/renderMarkdown.js b/lib/core/renderMarkdown.js
index cdac0be9b5..2f7062d87f 100644
--- a/lib/core/renderMarkdown.js
+++ b/lib/core/renderMarkdown.js
@@ -23,8 +23,8 @@ class MarkdownRenderer {
 
     const md = new Markdown({
       // Highlight.js expects hljs css classes on the code element.
-      // This results in <pre><code class="hljs css javascript">
-      langPrefix: 'hljs css languages- ',
+      // This results in <pre><code class="hljs css languages-jsx">
+      langPrefix: 'hljs css languages-',
       highlight: function(str, lang) {
         lang =
           lang || (siteConfig.highlight && siteConfig.highlight.defaultLang);