Hi all, there was a thread earlier this summer on the topic of the bootstrap: http://groups.google.com/group/fa.caml/browse_thread/thread/a39e6699f0c5043d I should add a tidbit of information that took me a while to figure out to the information there. The information from the thread is: "look at the comment 'Hard bootstrap how-to' in the toplevel Makefile of the OCaml [CVS] distribution" The additional tidbit is: if you are trying to add a new primitive, try splitting the patch in two parts, the part that contains the C primitive (the "CAMLprim ..." in a .c file) and the part that makes it visible from caml (the "external ..." in an .ml file). Apply the first patch only first, bootstrap, apply the second one and bootstrap again. I did not see this information explicitly documented anywhere, but it was implicitly contained in the following web page: http://www.pps.jussieu.fr/~henry/marshal/index.en.html Pascal