Stylus inline SVG without base64

How do I inline SVG images in CSS with Stylus without the images being converted to Base64 strings?

Like

background: url('data:image/svg+xml;utf8,<svg>[...]</svg>');

instead of:

background: url('data:image/svg+xml;base64,PD94bWwg[...]');

When I use stylus.url() the image is converted to Base64.