Dear list, I am trying to test my ocaml application using a test coverage tool called bisect (http://bisect.x9c.fr/index.html). This tool uses camlp4 to instrument the source code, i.e. adding the check points to say that the source code has been explored by the tests. When I try to instrument my application, I get the following error from camlp4: Parse error: [module_type] expected after ":" (in [module_declaration]) Error while running external preprocessor Is it possible that camlp4 does not support the functor feature of OCaml? Has anyone had this error before? I googled for the error string and similar errors, but I could not find anything promising. I also searched the archives of this mailing list and the wg-camlp4 mailing list, but nothing similar was present. The following source files raise the same error (they successfully compile though!): (* test.mli -------------- *) module type a = sig type t end module A (AO : a) : sig val f : AO.t -> bool end (* test.ml --------------- *) module type a = sig type t end module A (AO : a) = struct let f ( x : AO.t) = true end let _ = print_endline "test" (* ------------------------- *) I attached them and the Makefile that I am using to create the executable. If you want to reproduce the error, you need to have installed Ocaml 4.01, ocamlfind and the last version of bisect (the most comfortable installation is through OPAM: opam install ocamlfind opam install bisect). Thanks for your attention, Andrea Giugliano