diff --git a/sys/sys/ioccom.h b/sys/sys/ioccom.h
index 0329ac358491..13faba046719 100644
--- a/sys/sys/ioccom.h
+++ b/sys/sys/ioccom.h
@@ -1,92 +1,95 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 1982, 1986, 1990, 1993, 1994
  *	The Regents of the University of California.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  *	@(#)ioccom.h	8.3 (Berkeley) 1/9/95
  * $FreeBSD$
  */
 
 #ifndef	_SYS_IOCCOM_H_
 #define	_SYS_IOCCOM_H_
 
 /*
  * Ioctl's have the command encoded in the lower word, and the size of
  * any in or out parameters in the upper word.  The high 3 bits of the
  * upper word are used to encode the in/out status of the parameter.
  *
  *	 31 29 28                     16 15            8 7             0
  *	+---------------------------------------------------------------+
  *	| I/O | Parameter Length        | Command Group | Command       |
  *	+---------------------------------------------------------------+
  */
 #define	IOCPARM_SHIFT	13		/* number of bits for ioctl size */
 #define	IOCPARM_MASK	((1 << IOCPARM_SHIFT) - 1) /* parameter length mask */
 #define	IOCPARM_LEN(x)	(((x) >> 16) & IOCPARM_MASK)
 #define	IOCBASECMD(x)	((x) & ~(IOCPARM_MASK << 16))
 #define	IOCGROUP(x)	(((x) >> 8) & 0xff)
 
 #define	IOCPARM_MAX	(1 << IOCPARM_SHIFT) /* max size of ioctl */
 
 #define	IOC_VOID	0x20000000UL	/* no parameters */
 #define	IOC_OUT		0x40000000UL	/* copy out parameters */
 #define	IOC_IN		0x80000000UL	/* copy in parameters */
 #define	IOC_INOUT	(IOC_IN|IOC_OUT)/* copy parameters in and out */
 #define	IOC_DIRMASK	(IOC_VOID|IOC_OUT|IOC_IN)/* mask for IN/OUT/VOID */
 
 #define	_IOC(inout,group,num,len)	((unsigned long) \
 	((inout) | (((len) & IOCPARM_MASK) << 16) | ((group) << 8) | (num)))
 #define	_IO(g,n)	_IOC(IOC_VOID,	(g), (n), 0)
 #define	_IOWINT(g,n)	_IOC(IOC_VOID,	(g), (n), sizeof(int))
 #define	_IOR(g,n,t)	_IOC(IOC_OUT,	(g), (n), sizeof(t))
 #define	_IOW(g,n,t)	_IOC(IOC_IN,	(g), (n), sizeof(t))
 /* this should be _IORW, but stdio got there first */
 #define	_IOWR(g,n,t)	_IOC(IOC_INOUT,	(g), (n), sizeof(t))
 /* Replace length/type in an ioctl command. */
 #define	_IOC_NEWLEN(ioc, len) \
     (((~(IOCPARM_MASK << 16)) & (ioc)) | (((len) & IOCPARM_MASK) << 16))
 #define	_IOC_NEWTYPE(ioc, type)	_IOC_NEWLEN((ioc), sizeof(type))
 
 #ifdef _KERNEL
 
 #if defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD5) || \
     defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
 #define	IOCPARM_IVAL(x)	((int)(intptr_t)(void *)*(caddr_t *)(void *)(x))
 #endif
 
+#define	_IOC_INVALID	(_IOC_VOID|_IOC_INOUT)	/* Never valid cmd value,
+						   use as filler */
+
 #else
 
 #include <sys/cdefs.h>
 
 __BEGIN_DECLS
 int	ioctl(int, unsigned long, ...);
 __END_DECLS
 
 #endif
 
 #endif /* !_SYS_IOCCOM_H_ */