diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index d4e60ecbc..db34abb88 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,3 +1,7 @@
+2001-04-13  Robert Collins <rbtcollins@hotmail.com>
+
+	* libc/include/sys/unistd.h: Add pthread_atfork (Cygwin only).
+
 Thu Apr 12 23:11:00 2001  Corinna Vinschen <corinna@vinschen.de>
 
 	* libc/include/sys/errno.h: Add ECASECLASH to indicate case clash
diff --git a/newlib/libc/include/sys/unistd.h b/newlib/libc/include/sys/unistd.h
index 0fad0dccf..fc8c25acc 100644
--- a/newlib/libc/include/sys/unistd.h
+++ b/newlib/libc/include/sys/unistd.h
@@ -65,6 +65,9 @@ int	_EXFUN(nice, (int __nice_value ));
 off_t   _EXFUN(lseek, (int __fildes, off_t __offset, int __whence ));
 long    _EXFUN(pathconf, (const char *__path, int __name ));
 int     _EXFUN(pause, (void ));
+#ifdef __CYGWIN__
+int	_EXFUN(pthread_atfork, (void (*)(void), void (*)(void), void (*)(void)));
+#endif
 int     _EXFUN(pipe, (int __fildes[2] ));
 _READ_WRITE_RETURN_TYPE _EXFUN(read, (int __fd, void *__buf, size_t __nbyte ));
 int     _EXFUN(rmdir, (const char *__path ));