diff --git a/lib/components/ModalPortal.js b/lib/components/ModalPortal.js
index ad325958..e6662ab9 100644
--- a/lib/components/ModalPortal.js
+++ b/lib/components/ModalPortal.js
@@ -2,7 +2,7 @@ var React = require('react');
 var div = React.DOM.div;
 var focusManager = require('../helpers/focusManager');
 var scopeTab = require('../helpers/scopeTab');
-var cx = require('react/lib/cx');
+var cx = require('classnames');
 
 // so that our CSS is statically analyzable
 var CLASS_NAMES = {
diff --git a/package.json b/package.json
index 1a035df7..65d37710 100644
--- a/package.json
+++ b/package.json
@@ -40,9 +40,9 @@
     "webpack-dev-server": "1.6.5"
   },
   "peerDependencies": {
-    "react": ">=0.12.0"
+    "react": ">=0.12.0",
+    "classnames": "^1.2.0"
   },
-  "dependencies": {},
   "tags": [
     "react",
     "modal",