Signed-off-by: Martin Kletzander <mkletzan(a)redhat.com&gt; --- Notes: This is the simplest solution suggested to me by Rich and it works. Most of autotools are not friends with me, so the other approach I tried, with requiring at least OCaml 4.05.0, having this fix in only for OCaml < 4.06.0 and properly detecting and reporting that, was a bit ugly. You can see the configure.ac part of it here: http://ix.io/1L0o If that is preferred, then I can send that one instead. ocaml/nbd-c.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/ocaml/nbd-c.h b/ocaml/nbd-c.h index 558581850807..45ae64d77209 100644 --- a/ocaml/nbd-c.h +++ b/ocaml/nbd-c.h @@ -27,6 +27,11 @@ #include <caml/memory.h> #include <caml/mlvalues.h> +// Workaround for OCaml < 4.06.0 +#ifndef Bytes_val +#define Bytes_val(x) String_val(x) +#endif + extern void libnbd_finalize (value); extern void nbd_buffer_finalize (value);