Grunt problems - LESS Recess

I’ve not had this problem before, but I am receiving an error on a new site I am working on with a fresh copy of Roots.

When running grunt I get this:

Running "recess:dist" (recess) task
>> Parser error in assets\less\bootstrap\mixins.less
>>      643.   padding-right: (@grid-gutter-width / 2);
>>      644.   &:extend(.clearfix all);
>>      645. }
Warning:  Use --force to continue.

Aborted due to warnings.```

I've done a bit of Googling and I came across people having similar issues on a different app:

I appreciate this isn't necessarily a Roots issue, but I was wondering with any other Roots users were experiencing the same issues. I don't know what the problem is and am wondering if any of you know how I can get this to work.

We dropped grunt-recess in favour of grunt-contrib-less a while back. Have you copied over an old Gruntfile?

Strange, maybe I did. I’ll have another go…

Oh pants, so sorry. Must have inadvertently copied over an old copy of Roots. Thanks for your help.

No worries. It’s easy enough to do.