Created attachment 1952137 [details] ocaml-newt-c99.patch Two functions miss the required value return type in the newt_int_stubs_by_hand.c file. For newt_stubs_newtComponentAddCallback (returning unit), that is probably inconsequential, but for newt_stubs_newtComponentAddress (returning int64), it looks like a real bug. Filing this here because there's no separate upstream (bug tracker).