diff --git a/README.md b/README.md
index 573b1959..3137f5d3 100644
--- a/README.md
+++ b/README.md
@@ -582,15 +582,15 @@ Reveal.addEventListener( 'fragmenthidden', function( event ) {
 
 ### Code syntax highlighting
 
-By default, Reveal is configured with [highlight.js](http://softwaremaniacs.org/soft/highlight/en/) for code syntax highlighting. Below is an example with clojure code that will be syntax highlighted. When the `data-trim` attribute is present surrounding whitespace is automatically removed.
+By default, Reveal is configured with [highlight.js](http://softwaremaniacs.org/soft/highlight/en/) for code syntax highlighting. Below is an example with clojure code that will be syntax highlighted. When the `data-trim` attribute is present, surrounding whitespace is automatically removed.  HTML will be escaped by default. To avoid this, for example if you are using `<mark>` to call out a line of code, add the `data-noescape` attribute to the `<code>` element.
 
 ```html
 <section>
-	<pre><code data-trim>
+	<pre><code data-trim data-noescape>
 (def lazy-fib
   (concat
    [0 1]
-   ((fn rfib [a b]
+   <mark>((fn rfib [a b]</mark>
         (lazy-cons (+ a b) (rfib b (+ a b)))) 0 1)))
 	</code></pre>
 </section>