--- term.c	2007-08-30 06:46:50.000000000 +0900
+++ term.c.fixed	2007-09-01 10:39:51.906250000 +0900
@@ -3142,8 +3142,10 @@
         emacs_close (fd);
       sigunblock (sigmask (SIGTTOU));
 #else
+#ifndef CYGWIN
       /* Unknown system. */
       croak ();
+#endif  /* ! CYGWIN */
 #endif  /* ! TIOCNOTTY */
 #endif  /* ! USG */
     }