diff --git a/lib/main/build-site.js b/lib/main/build-site.js
index dc8819c55..139ae32fd 100644
--- a/lib/main/build-site.js
+++ b/lib/main/build-site.js
@@ -28,6 +28,8 @@ const highlights = {
   ]
 };
 
+const exts = _.keys(highlights);
+
 /**
  * Converts Lodash method references into documentation links.
  *
@@ -117,7 +119,8 @@ function tidyHighlights($) {
   $('.highlight').each(function() {
     let $spans;
     const $parent = $(this);
-    const ext = $parent.find('.source,.text').first().attr('class').split(' ').pop();
+    const classes = $parent.find('.source,.text').first().attr('class').split(' ');
+    const ext = _(classes).intersection(exts).last();
 
     $parent.addClass(ext);
 
@@ -132,7 +135,7 @@ function tidyHighlights($) {
     $parent.find('[class]').each(function() {
       const $element = $(this);
       const classes = $element.attr('class').split(' ');
-      const attr = _.intersection(classes, highlights[ext]).join(' ');
+      const attr = _(classes).intersection(highlights[ext]).join(' ');
       $element.attr('class', attr || null);
     });
     // Collapse nested comment highlights.