--- a/toolkit/modules/RemotePageManager.jsm
+++ b/toolkit/modules/RemotePageManager.jsm
@@ -164,16 +164,22 @@ function publicMessagePort(port) {
   let properties = ["addMessageListener", "removeMessageListener",
                     "sendAsyncMessage", "destroy"];
 
   let clean = {};
   for (let property of properties) {
     clean[property] = port[property].bind(port);
   }
 
+  Object.defineProperty(clean, "portID", {
+    get() {
+      return port.portID;
+    }
+  });
+
   if (port instanceof ChromeMessagePort) {
     Object.defineProperty(clean, "browser", {
       get() {
         return port.browser;
       }
     });
   }