Compass can't resolve relative image path

Scenario

File structure:

ui/components/gritter/gritter.scss
ui/components/gritter/images/gritter.png
ui/images/foo.jpg

Gritter.scss

.bottom
{
   background: image-url("images/gritter.png");
}

And my compass config:

images_dir = '/'
project_path = "ui/"

Problem

When I compile, compass tries to resolve the image path to /ui/images/gritter.png, which does not exist.

How can I make compass to look for images relative to tue .scss file before trying to resolve it to project_path + images_dir?