diff --git a/src/TreeMenu.jsx b/src/TreeMenu.jsx
index 380f9d2..85c9936 100644
--- a/src/TreeMenu.jsx
+++ b/src/TreeMenu.jsx
@@ -38,7 +38,7 @@ var TreeMenu = React.createClass({
     checkboxFactory: React.PropTypes.func,
     sort: React.PropTypes.oneOfType([
       React.PropTypes.bool,
-      React.PropTypes.function
+      React.PropTypes.func
     ])
   },