Update HTML5 canvas rectangle on hover?

Question

I've got some code which draws a rectangle on a canvas, but I want that rectangle to change color when I hover the mouse over it.

The problem is after I've drawn the rectangle I'm not sure how I select it again to make the adjustment.

What I want to do:

var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.rect(20,20,150,100);
ctx.stroke();

$('c.[rectangle]').hover(function(this){
    this.fillStyle = 'red';
    this.fill();
});