diff --git a/sysdeps/unix/bsd/sun/sunos4/tcflow.c b/sysdeps/unix/bsd/sun/sunos4/tcflow.c
new file mode 100644
index 0000000000..5accafd47c
--- /dev/null
+++ b/sysdeps/unix/bsd/sun/sunos4/tcflow.c
@@ -0,0 +1,28 @@
+/* Copyright (C) 1993 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <errno.h>
+#include <termios.h>
+
+/* Suspend or restart transmission on FD.  */
+int
+DEFUN(tcflow, (fd, action), int fd AND int action)
+{
+  return __ioctl (fd, TCXONC, action);
+}