Covariance issue?

[Ptival]

I have a setup where

class Child extends Parent { ... }

But upon a function call I get the following error:

Argument of type 'Maybe<Child>' is not assignable to parameter of type 'Maybe<Parent>'.

Is there a known workaround, or am I to use casts?

[Ptival]

Nevermind, got it working on a smaller example, I think I did something wrong.