Cannot run node js app listening on 443

I've got a socket application that I'm trying to make listen on port 443 (https). If I change the port (to e.g. 8080) I get no problems.

The error shown is

error raised: Error: listen EACCES

My app source code is:

var fs = require('fs');

// create the https server and listen on port
var options = {
    ca:   fs.readFileSync('ca.pem'),
    cert: fs.readFileSync('cert.pem'),
    key:  fs.readFileSync('server.key')
};

var server = require('https').createServer(options);
var portNo = 443;
var app = server.listen(portNo, function() {
  console.log((new Date()) + " Server is listening on port " + portNo);
});

// create the socket server on the port
var io = require('socket.io').listen(app);


// This callback function is called every time a socket
// tries to connect to the server
io.sockets.on('connection', function (socket) {

    console.log((new Date()) + ' Connection established.');

    // When a user send a SDP message
    // broadcast to all users in the room
    socket.on('message', function (message) {
        socket.broadcast.emit('message', message);
    });

    // When the user hangs up
    // broadcast bye signal to all users in the room
    socket.on('disconnect', function () {
        // close user connection
        console.log((new Date()) + " Peer disconnected.");
        socket.broadcast.emit('user disconnected');
    });
});

I've seen plenty of answers relating to Linux telling them to run as sudo so I tried running the node server as administrator but to no avail.

This is running on a Windows Server 2012 box.

Thanks.