Support for case-insensitive matching of literals?

I apologise if I missed this somewhere, but I have a grammar with a lot of string literals that are case insensitive, and I cannot find anything in the docs about how to parse this best, here's one example:

`unary_operator <- ~("abs" / "acos" / "asin" / "atan" / "cos" / "exp" / "fix" / "fup" / "ln" / "round" / "sin" / "sqrt" / "tan")`

The best I've been able to do is to replace every literal with a combination of class matches, e.g. `[aA][bB][sS]` instead of "abs", which I guess works but does become tedious, so I just wanted to check if there's something I'm missing!