diff --git a/README.md b/README.md
index f997daeafd91f84607942956c6ffc7b0ca71a017..52c3fc30c4ca720cb87a55d49dca49eabb8dc634 100644
--- a/README.md
+++ b/README.md
@@ -370,6 +370,8 @@ The display order of fragments can be controlled using the ```data-fragment-inde
 
 When a slide fragment is either shown or hidden reveal.js will dispatch an event.
 
+Some libraries, like MathJax (see #505), get confused by the initially hidden fragment elements. Often times this can be fixed by calling their update or render function from this callback.
+
 ```javascript
 Reveal.addEventListener( 'fragmentshown', function( event ) {
 	// event.fragment = the fragment DOM element