Module "mypy_extensions" has no attribute "u8"

[JotaRata]

I'm unable to compile my code that makes use of mypyc native integer types
The console output only says:
error: Module "mypy_extensions" has no attribute "u8" [attr-defined]

Is there something I'm missing, like to include a module path?
I have no errors using mypy alone, it just appears when try to compile.

I can however, use traits and mypyc_attr