This is building on Cygwin. I get this error: gcc -c -I/usr/lib/../include/noX -I/usr/lib/../include/noX -g -O3 -Wall -Wno-switch -Winline -Wmissing-prototypes -Wsign-compare -Wshadow -Wpointer-arith -Demacs -I. -DHAVE_CONFIG_H -fno-caller-saves -fvtable-thunks events.c events.c: In function `event_equal': events.c:447: sizeof applied to an incomplete type It appears that the HAVE_MS_MSWINDOWS section should look more like the X and Gtk cases: #ifdef HAVE_MS_WINDOWS if (CONSOLE_MSWINDOWS_P (con)) return (XMAGIC_DATA_MSWINDOWS_EVENT (EVENT_DATA(e1)) = XMAGIC_DATA_MSWINDOWS_EVENT (EVENT_DATA (e2))); #endif I'll submit a patch if others think this looks correct. david