This might be related to https://github.com/less/less.js/issues/3405: ```less .mix (@n) { value: @n; } @var: .mix(var); #lookup { @var: .mix(lookup); @bar: bar; } .example { @var(); value2: #lookup[@bar]; // This is what I'm trying to do, since the above works: #lookup[@var](); } ``` Expected: ```css .example { value: lookup; value2: bar; } ``` Actual: unexpected token. In this case I can't find a workaround using detached rulesets, but since `@var()` works I expect the nested syntax `#lookup[@var]()` to work as well.