Compiler problem with icons.less and sprites.less

[nexxome]

My compiler (winless) doesn't compile if I import icons.less or sprites.less. It shows no error so I tested it with less.js with this result:

b.value is undefined

in icons.less
@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
t@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
t@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
t@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
@http://127.0.0.1/testing/js/less-1.3.0.min.js:8
...

I did some research to find the lines which causes this error and discovered that it is a problem with the combination of an image url and a variable.

sprites.less

Line 33: background-image: url(@sprite-image);

icons.less

Line 192: background: url(@icon-image) no-repeat 0 0;
Line 202: background: url(@icon-image) no-repeat 0 0;
Line 212: background: url(@icon-image) no-repeat 0 0;
Line 222: background: url(@icon-image) no-repeat 0 0;
Line 236: background: url(@icon-image) no-repeat 0 0;

If I remove these lines it works.