Draw a ring using the HTML5 canvas without the straight line

I want to draw a ring with the canvas that doesn’t have the straight black line you see when you use the below code.

 var can = document.getElementById('canvas1');
 var ctx = can.getContext('2d');
 //ctx.arc(x,y,radius,startAngle,endAngle, anticlockwise);  
 ctx.beginPath()
 ctx.arc(100,100,100,0,Math.PI*2,false); // outer (filled)
 ctx.arc(100,100,55,0,Math.PI*2,true); // outer (unfills it)
 ctx.fillStyle='red';
 ctx.fill();
 ctx.strokeStyle='black';
 ctx.lineWidth=1;
 ctx.stroke();

<canvas id="canvas1" width="800" height="800"></canvas>