Unable to Operate Variables in Font Property

[alixaxel]

The following:

@typeSize: 12px;
@typeRhythm: 1.5;
@typeFamily: "Helvetica Neue", Helvetica, "Helvetica Sans Unicode", Arial, sans-serif;

html {
    font: @typeSize ~'/' @typeRhythm @typeFamily;
    font-size: @typeSize;
    line-height: @typeSize * @typeRhythm;
}

Works, and produces the following CSS:

html {
  font:12px / 1.5 "Helvetica Neue",Helvetica,"Helvetica Sans Unicode",Arial,sans-serif;
  font-size:12px;
  line-height:18px;
}

However, if I change the source to:

@typeSize: 12px;
@typeRhythm: 1.5;
@typeFamily: "Helvetica Neue", Helvetica, "Helvetica Sans Unicode", Arial, sans-serif;

html {
    font: @typeSize ~'/' (@typeSize * @typeRhythm) @typeFamily;
    font-size: @typeSize;
    line-height: @typeSize * @typeRhythm;
}

I get a syntax error.

[lukeapage]

Fixed on master for 1.4.0