diff --git a/lib/wsapp.js b/lib/wsapp.js
index a4d69e3..a2544d0 100644
--- a/lib/wsapp.js
+++ b/lib/wsapp.js
@@ -21,10 +21,7 @@ log.level = 'debug';
 
 var io;
 var blockExplorerSockets = {};
-var subscriptions = {
-  wallets: {},
-  addresses: {},
-};
+var subscriptions = {};
 
 var WsApp = function() {};
 
@@ -34,11 +31,13 @@ WsApp._unauthorized = function() {
 };
 
 WsApp.subscribeAddresses = function(walletId, addresses) {
+  $.checkArgument(walletId);
+
   if (!addresses || addresses.length == 0) return;
 
-  function handlerFor(walletId, address, txid) {
+  function handlerFor(address, txid) {
     var notification = Notification.create({
-      walletId: walletId,
+      walletId: this,
       type: 'NewIncomingTx',
       data: {
         address: address,
@@ -48,24 +47,28 @@ WsApp.subscribeAddresses = function(walletId, addresses) {
     WsApp._sendNotification(notification);
   };
 
+  if (!subscriptions[walletId]) {
+    subscriptions[walletId] = {
+      addresses: [],
+    };
+  };
   var addresses = [].concat(addresses);
   var network = Bitcore.Address.fromString(addresses[0]).network;
   var socket = blockExplorerSockets[network];
   _.each(addresses, function(address) {
-    subscriptions[address] = walletId;
+    subscriptions[walletId].addresses.push(address);
     socket.emit('subscribe', address);
-    socket.on(address, _.bind(handlerFor, null, walletId, address));
+    socket.on(address, _.bind(handlerFor, walletId, address));
   });
 };
 
 WsApp.subscribeWallet = function(serviceInstance) {
   var walletId = serviceInstance.walletId;
-  if (subscriptions.wallets[walletId]) return;
+  if (subscriptions[walletId]) return;
 
-  subscriptions.wallets[walletId] = true;
   serviceInstance.getMainAddresses({}, function(err, addresses) {
     if (err) {
-      delete subscriptions.wallets[walletId];
+      delete subscriptions[walletId];
       log.warn('Could not subscribe to addresses for wallet ' + serviceInstance.walletId);
       return;
     }