diff --git a/ChangeLog b/ChangeLog
index e3995421a6..b373406c03 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-05-10  Samuel Thibault  <samuel.thibault@ens-lyon.org>
+
+	* sysdeps/mach/hurd/bits/ioctls.h (_IOIW): New macro for
+	immediate-write ioctls.
+	* sysdeps/mach/hurd/ioctl.c: Handle cases with no arguments.
+
 2012-05-10  Thomas Schwinge  <thomas@schwinge.name>
 
 	* sysdeps/mach/hurd/i386/init-first.c (init): Use
diff --git a/sysdeps/mach/hurd/bits/ioctls.h b/sysdeps/mach/hurd/bits/ioctls.h
index 65f2ec1dd0..c4cfce65a3 100644
--- a/sysdeps/mach/hurd/bits/ioctls.h
+++ b/sysdeps/mach/hurd/bits/ioctls.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 1992,93,96,97,98,99,2001,2007 Free Software Foundation, Inc.
+/* Copyright (C) 1992-2012 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
@@ -157,6 +157,7 @@ enum __ioctl_datum { IOC_8, IOC_16, IOC_32, IOC_64 };
    _IOT_foobar is defined either in this file,
    or where struct foobar is defined.  */
 #define	_IO(g, n)	_IOC (IOC_VOID, (g), (n), 0)
+#define	_IOIW(g, n, t)	_IOC (IOC_VOID, (g), (n), _IOC_ENCODE_TYPE (t))
 #define	_IOR(g, n, t)	_IOC (IOC_OUT, (g), (n), _IOC_ENCODE_TYPE (t))
 #define	_IOW(g, n, t)	_IOC (IOC_IN, (g), (n), _IOC_ENCODE_TYPE (t))
 #define	_IOWR(g, n, t)	_IOC (IOC_INOUT, (g), (n), _IOC_ENCODE_TYPE (t))
diff --git a/sysdeps/mach/hurd/ioctl.c b/sysdeps/mach/hurd/ioctl.c
index beffe4365e..543d437c1e 100644
--- a/sysdeps/mach/hurd/ioctl.c
+++ b/sysdeps/mach/hurd/ioctl.c
@@ -1,5 +1,4 @@
-/* Copyright (C) 1992,93,94,95,96,97,99,2000,2002,2005
-	Free Software Foundation, Inc.
+/* Copyright (C) 1992-2012 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
@@ -88,7 +87,7 @@ __ioctl (int fd, unsigned long int request, ...)
   void *p;
 #endif
 
-  void *arg;
+  void *arg = NULL;
 
   error_t err;
 
@@ -111,7 +110,7 @@ __ioctl (int fd, unsigned long int request, ...)
       if (_IOC_INOUT (request) & IOC_IN)
 	{
 	  /* We don't want to advance ARG since it will be used to copy out
-             too if IOC_OUT is also set.  */
+	     too if IOC_OUT is also set.  */
 	  void *argptr = arg;
 
 	  /* Pack an argument into the message buffer.  */
@@ -139,7 +138,7 @@ __ioctl (int fd, unsigned long int request, ...)
 	  in (_IOT_COUNT1 (type), _IOT_TYPE1 (type));
 	  in (_IOT_COUNT2 (type), _IOT_TYPE2 (type));
 	}
-      else if (_IOC_INOUT (request) == IOC_VOID)
+      else if (_IOC_INOUT (request) == IOC_VOID && _IOT_COUNT0 (type) != 0)
 	{
 	  /* The RPC takes a single integer_t argument.
 	     Rather than pointing to the value, ARG is the value itself.  */
@@ -208,11 +207,15 @@ __ioctl (int fd, unsigned long int request, ...)
       return msg.header.RetCode;
     }
 
-  va_list ap;
+  if (_IOT_COUNT0 (type) != 0)
+    {
+      /* Data need either be sent, received, or even both.  */
+      va_list ap;
 
-  va_start (ap, request);
-  arg = va_arg (ap, void *);
-  va_end (ap);
+      va_start (ap, request);
+      arg = va_arg (ap, void *);
+      va_end (ap);
+    }
 
   {
     /* Check for a registered handler for REQUEST.  */