diff --git a/lib/Controller.js b/lib/Controller.js
index 387413f..02f0dda 100644
--- a/lib/Controller.js
+++ b/lib/Controller.js
@@ -55,7 +55,7 @@ function Controller(client, options) {
     // Register the listener on navdata for our control loop
     var self = this;
     client.on('navdata', function(d) {
-        if (!this._busy) {
+        if (!this._busy && d.demo) {
             this._busy = true;
             self._processNavdata(d);
             self._control(d);