diff --git a/lib/components/Modal.js b/lib/components/Modal.js
index 8efb9ab1..1d45cc45 100644
--- a/lib/components/Modal.js
+++ b/lib/components/Modal.js
@@ -1,8 +1,11 @@
 var React = require('react');
+var ExecutionEnvironment = require('react/lib/ExecutionEnvironment');
 var ModalPortal = React.createFactory(require('./ModalPortal'));
 var ariaAppHider = require('../helpers/ariaAppHider');
 var injectCSS = require('../helpers/injectCSS');
 
+var SafeHTMLElement = ExecutionEnvironment.canUseDOM ? window.HTMLElement : {};
+
 var Modal = module.exports = React.createClass({
 
   displayName: 'Modal',
@@ -15,7 +18,7 @@ var Modal = module.exports = React.createClass({
   propTypes: {
     isOpen: React.PropTypes.bool.isRequired,
     onRequestClose: React.PropTypes.func,
-    appElement: React.PropTypes.instanceOf(HTMLElement),
+    appElement: React.PropTypes.instanceOf(SafeHTMLElement),
     closeTimeoutMS: React.PropTypes.number,
     ariaHideApp: React.PropTypes.bool
   },