diff --git a/newlib/ChangeLog b/newlib/ChangeLog
index b1a026f0b..6ba5a9a52 100644
--- a/newlib/ChangeLog
+++ b/newlib/ChangeLog
@@ -1,3 +1,8 @@
+2004-04-10  Corinna Vinschen  <corinna@vinschen.de>
+
+	* libc/include/sys/unistd.h (sync): Define void on Cygwin according
+	to SUSv3.
+
 2004-04-08  Artem B. Bityuckiy  <abitytsky@softminecorp.com>
 
 	* libc/stdio/fclose.c (_fclose_r): New function.
diff --git a/newlib/libc/include/sys/unistd.h b/newlib/libc/include/sys/unistd.h
index 6a49d5d47..4a3288322 100644
--- a/newlib/libc/include/sys/unistd.h
+++ b/newlib/libc/include/sys/unistd.h
@@ -202,7 +202,11 @@ unsigned _EXFUN(usleep, (unsigned int __useconds));
  int	_EXFUN(gethostname, (char *__name, size_t __len));
 #endif
 char *	_EXFUN(mktemp, (char *));
+#if defined(__CYGWIN__)
+void    _EXFUN(sync, (void));
+#else /* defined(__rtems__) */
 int     _EXFUN(sync, (void));
+#endif
 int     _EXFUN(readlink, (const char *__path, char *__buf, int __buflen));
 int     _EXFUN(symlink, (const char *__name1, const char *__name2));
 #endif