The file /usr/X11R6/include/X11/Xarch.h contains a reference to endian.h. That file was not in my distribution. I found one on my linux partition and copied it plus bits/endian.h to the cygwin /usr/include directory and it worked. Uname returns CYGWIN_NT-5.1. I am amazed at how much XFree86 makes cygwin feel like linux. Thanks, Bob wilson