diff --git a/app/assets/javascripts/discourse/lib/syntax_highlighting.js b/app/assets/javascripts/discourse/lib/syntax_highlighting.js
index 34477c126..806b8aaa2 100644
--- a/app/assets/javascripts/discourse/lib/syntax_highlighting.js
+++ b/app/assets/javascripts/discourse/lib/syntax_highlighting.js
@@ -16,7 +16,7 @@ Discourse.SyntaxHighlighting = {
     @param {jQuery.selector} $elem The element we want to apply our highlighting to
   **/
   apply: function($elem) {
-    $('pre code', $elem).each(function(i, e) {
+    $('pre code[class]', $elem).each(function(i, e) {
       return $LAB.script("/javascripts/highlight.pack.js").wait(function() {
         return hljs.highlightBlock(e);
       });