Node.js w/ fibers eat all RAM when fibers are created in a tight loop

Question

The following program, when run, progressively eats all RAM:

var Fiber = require('fibers');

function f()
{
  console.log('In a fiber');
}

for (;;)
{
  var fiber = new Fiber(f);
  fiber.run();
}

Apparently, all the fibers created by it are never garbage-collected. How can I make sure that my past fibers are deallocated in a timely fashion?