Stylus inline SVG data uri without base64 encoding

How can I embed a SVG data uri in CSS using Stylus preprocessor without the SVG being Base64 encoded?

Like this:

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

instead of this:

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

Normaly I've used stylus.url() to embed images, but it will also Base64 encode SVGs.

I want to use data uris instead of external files to save file requests. And I've realised that Base64 encoding SVGs actually adds bytes instead of reducing size.

I can't find a method to embed the SVG as-is.