diff --git a/src/react-components/ui-root.js b/src/react-components/ui-root.js
index 946784e9e1f6e18aa6a412a86d350f39a1772a24..3970a2305c4439900b4936f8e465d2d0039a8de0 100644
--- a/src/react-components/ui-root.js
+++ b/src/react-components/ui-root.js
@@ -60,7 +60,7 @@ class UIRoot extends Component {
     enableScreenSharing: PropTypes.bool,
     store: PropTypes.object,
     scene: PropTypes.object,
-    htmlPrefix: PropTypes.object
+    htmlPrefix: PropTypes.string
   };
 
   state = {