Here is a patch to add support to the upcoming OCaml 5.0 to hivex: https://github.com/kit-ty-kate/hivex/commit/e89b4ab014fa764bf392275ba0dfa7631ea7689b

This new release of the compiler will be released early next month.

Note: this patch breaks support for OCaml < 4.07. If you want to keep support I suppose you can add some hacks in the configure.ac file to add "module Stdlib = Pervasives" at the start of the "generator/generator.ml" file but I'm not sure how worth to you it is to support old +5 years old compilers.

Kind regards,