diff --git a/lib/client.js b/lib/client.js
index 71ec38b095..1ce3fc4986 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -28,7 +28,7 @@ function Client(server, conn){
   this.id = conn.id;
   this.request = conn.request;
   this.setup();
-  this.sockets = [];
+  this.sockets = {};
   this.nsps = {};
   this.connectBuffer = [];
 }
@@ -73,7 +73,7 @@ Client.prototype.connect = function(name){
 
   var self = this;
   var socket = nsp.add(this, function(){
-    self.sockets.push(socket);
+    self.sockets[socket.id] = socket;
     self.nsps[nsp.name] = socket;
 
     if ('/' == nsp.name && self.connectBuffer.length > 0) {
@@ -90,12 +90,10 @@ Client.prototype.connect = function(name){
  */
 
 Client.prototype.disconnect = function(){
-  var socket;
-  // we don't use a for loop because the length of
-  // `sockets` changes upon each iteration
-  while (socket = this.sockets.shift()) {
-    socket.disconnect();
+  for (var id in this.sockets) {
+    this.sockets[id].disconnect();
   }
+  this.sockets = {};
   this.close();
 };
 
@@ -106,10 +104,9 @@ Client.prototype.disconnect = function(){
  */
 
 Client.prototype.remove = function(socket){
-  var i = this.sockets.indexOf(socket);
-  if (~i) {
-    var nsp = this.sockets[i].nsp.name;
-    this.sockets.splice(i, 1);
+  if (this.sockets[socket.id]) {
+    var nsp = this.sockets[socket.id].nsp.name;
+    delete this.sockets[socket.id];
     delete this.nsps[nsp];
   } else {
     debug('ignoring remove for %s', socket.id);
@@ -206,9 +203,9 @@ Client.prototype.ondecoded = function(packet) {
  */
 
 Client.prototype.onerror = function(err){
-  this.sockets.forEach(function(socket){
-    socket.onerror(err);
-  });
+  for (var id in this.sockets) {
+    this.sockets[id].onerror(err);
+  }
   this.onclose('client error');
 };
 
@@ -226,10 +223,10 @@ Client.prototype.onclose = function(reason){
   this.destroy();
 
   // `nsps` and `sockets` are cleaned up seamlessly
-  var socket;
-  while (socket = this.sockets.shift()) {
-    socket.onclose(reason);
+  for (var id in this.sockets) {
+    this.sockets[id].onclose(reason);
   }
+  this.sockets = {};
 
   this.decoder.destroy(); // clean up decoder
 };
diff --git a/lib/index.js b/lib/index.js
index 449fb6fa12..1612c0cfa3 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -347,9 +347,9 @@ Server.prototype.of = function(name, fn){
  */
 
 Server.prototype.close = function(){
-  this.nsps['/'].sockets.forEach(function(socket){
-    socket.onclose();
-  });
+  for (var id in this.nsps['/'].sockets) {
+    this.nsps['/'].sockets[id].onclose();
+  }
 
   this.engine.close();
 
diff --git a/lib/namespace.js b/lib/namespace.js
index 11c231dc38..1a5b7efcfd 100644
--- a/lib/namespace.js
+++ b/lib/namespace.js
@@ -51,7 +51,7 @@ var emit = Emitter.prototype.emit;
 function Namespace(server, name){
   this.name = name;
   this.server = server;
-  this.sockets = [];
+  this.sockets = {};
   this.connected = {};
   this.fns = [];
   this.ids = 0;
@@ -160,7 +160,7 @@ Namespace.prototype.add = function(client, fn){
         if (err) return socket.error(err.data || err.message);
 
         // track socket
-        self.sockets.push(socket);
+        self.sockets[socket.id] = socket;
 
         // it's paramount that the internal `onconnect` logic
         // fires before user-set events to prevent state order
@@ -187,9 +187,8 @@ Namespace.prototype.add = function(client, fn){
  */
 
 Namespace.prototype.remove = function(socket){
-  var i = this.sockets.indexOf(socket);
-  if (~i) {
-    this.sockets.splice(i, 1);
+  if (this.sockets[socket.id]) {
+    delete this.sockets[socket.id];
   } else {
     debug('ignoring remove for %s', socket.id);
   }
diff --git a/lib/socket.js b/lib/socket.js
index eeb8cb2159..1e50a0232b 100644
--- a/lib/socket.js
+++ b/lib/socket.js
@@ -60,9 +60,10 @@ function Socket(nsp, client){
   this.server = nsp.server;
   this.adapter = this.nsp.adapter;
   this.id = client.id;
+  this.id = nsp.name + '#' + client.id;
   this.client = client;
   this.conn = client.conn;
-  this.rooms = [];
+  this.rooms = {};
   this.acks = {};
   this.connected = true;
   this.disconnected = false;
@@ -222,11 +223,11 @@ Socket.prototype.packet = function(packet, opts){
 Socket.prototype.join = function(room, fn){
   debug('joining room %s', room);
   var self = this;
-  if (~this.rooms.indexOf(room)) return this;
+  if (this.rooms[room]) return this;
   this.adapter.add(this.id, room, function(err){
     if (err) return fn && fn(err);
     debug('joined room %s', room);
-    self.rooms.push(room);
+    self.rooms[room] = room;
     fn && fn(null);
   });
   return this;
@@ -247,10 +248,7 @@ Socket.prototype.leave = function(room, fn){
   this.adapter.del(this.id, room, function(err){
     if (err) return fn && fn(err);
     debug('left room %s', room);
-    var idx = self.rooms.indexOf(room);
-    if (idx >= 0) {
-      self.rooms.splice(idx, 1);
-    }
+    delete self.rooms[room];
     fn && fn(null);
   });
   return this;
@@ -264,7 +262,7 @@ Socket.prototype.leave = function(room, fn){
 
 Socket.prototype.leaveAll = function(){
   this.adapter.delAll(this.id);
-  this.rooms = [];
+  this.rooms = {};
 };
 
 /**
diff --git a/test/socket.io.js b/test/socket.io.js
index 06b1c77362..026cb5f143 100644
--- a/test/socket.io.js
+++ b/test/socket.io.js
@@ -368,12 +368,12 @@ describe('socket.io', function(){
       var clientSocket = client(srv, { reconnection: false });
 
       clientSocket.on('disconnect', function init() {
-        expect(sio.nsps['/'].sockets.length).to.equal(0);
+        expect(Object.keys(sio.nsps['/'].sockets).length).to.equal(0);
         server.listen(PORT);
       });
 
       clientSocket.on('connect', function init() {
-        expect(sio.nsps['/'].sockets.length).to.equal(1);
+        expect(Object.keys(sio.nsps['/'].sockets).length).to.equal(1);
         sio.close();
       });
 
@@ -395,12 +395,12 @@ describe('socket.io', function(){
       var clientSocket = ioc('ws://0.0.0.0:' + PORT);
 
       clientSocket.on('disconnect', function init() {
-        expect(sio.nsps['/'].sockets.length).to.equal(0);
+        expect(Object.keys(sio.nsps['/'].sockets).length).to.equal(0);
         server.listen(PORT);
       });
 
       clientSocket.on('connect', function init() {
-        expect(sio.nsps['/'].sockets.length).to.equal(1);
+        expect(Object.keys(sio.nsps['/'].sockets).length).to.equal(1);
         sio.close();
       });
 
@@ -1932,15 +1932,15 @@ describe('socket.io', function(){
         var socket = client(srv);
         sio.on('connection', function(s){
           s.join('a', function(){
-            expect(s.rooms).to.eql([s.id, 'a']);
+            expect(Object.keys(s.rooms)).to.eql([s.id, 'a']);
             s.join('b', function(){
-              expect(s.rooms).to.eql([s.id, 'a', 'b']);
+              expect(Object.keys(s.rooms)).to.eql([s.id, 'a', 'b']);
               s.join( 'c', function(){
-                expect(s.rooms).to.eql([s.id, 'a', 'b', 'c']);
+                expect(Object.keys(s.rooms)).to.eql([s.id, 'a', 'b', 'c']);
                 s.leave('b', function(){
-                  expect(s.rooms).to.eql([s.id, 'a', 'c']);
+                  expect(Object.keys(s.rooms)).to.eql([s.id, 'a', 'c']);
                   s.leaveAll();
-                  expect(s.rooms).to.eql([]);
+                  expect(Object.keys(s.rooms)).to.eql([]);
                   done();
                 });
               });
@@ -1976,13 +1976,13 @@ describe('socket.io', function(){
         var socket = client(srv);
         sio.on('connection', function(s){
           s.join('a', function(){
-            expect(s.rooms).to.eql([s.id, 'a']);
+            expect(Object.keys(s.rooms)).to.eql([s.id, 'a']);
             s.join('b', function(){
-              expect(s.rooms).to.eql([s.id, 'a', 'b']);
+              expect(Object.keys(s.rooms)).to.eql([s.id, 'a', 'b']);
               s.leave('unknown', function(){
-                expect(s.rooms).to.eql([s.id, 'a', 'b']);
+                expect(Object.keys(s.rooms)).to.eql([s.id, 'a', 'b']);
                 s.leaveAll();
-                expect(s.rooms).to.eql([]);
+                expect(Object.keys(s.rooms)).to.eql([]);
                 done();
               });
             });