Error in less formula

[LttleSwill]

I have the following in my less -
width: calc(50% - 40px);

but this gets generated as -
width: calc(10%);

I suspect it doesn't respect the different units. The former seems to be valid css to me.

[NDaskalov]

That is not an issue!
just use
width: calc(~'(50% - 40px)');