diff --git a/lib/components/Modal.js b/lib/components/Modal.js
index 0fb48f26..f4b79950 100644
--- a/lib/components/Modal.js
+++ b/lib/components/Modal.js
@@ -65,14 +65,16 @@ var Modal = React.createClass({
   },
 
   renderPortal: function(props) {
-    if (props.isOpen) {
-      elementClass(document.body).add('ReactModal__Body--open');
-    } else {
-      elementClass(document.body).remove('ReactModal__Body--open');
-    }
+    if (this.props.isOpen !== props.isOpen) {
+      if (props.isOpen) {
+        elementClass(document.body).add('ReactModal__Body--open');
+      } else {
+        elementClass(document.body).remove('ReactModal__Body--open');
+      }
 
-    if (props.ariaHideApp) {
-      ariaAppHider.toggle(props.isOpen, props.appElement);
+      if (props.ariaHideApp) {
+        ariaAppHider.toggle(props.isOpen, props.appElement);
+      }
     }
 
     this.portal = renderSubtreeIntoContainer(this, ModalPortal(Assign({}, props, {defaultStyles: Modal.defaultStyles})), this.node);