diff --git a/lib/zmq_service.js b/lib/zmq_service.js
index <HASH>..<HASH> 100644
--- a/lib/zmq_service.js
+++ b/lib/zmq_service.js
@@ -9,7 +9,8 @@
   var ZMQService = function(configuration){
     var defaults = {
       broker: 'tcp://127.0.0.1:5560',
-      heartbeat: 1000
+      heartbeat: 1000,
+      sid: null
     };
 
     var config = _.defaults(configuration, defaults);
added default sid property to null