diff --git a/sys/compat/linux/linux_sysctl.c b/sys/compat/linux/linux_sysctl.c
index 65c64a7ba563..97341c051af7 100644
--- a/sys/compat/linux/linux_sysctl.c
+++ b/sys/compat/linux/linux_sysctl.c
@@ -1,168 +1,168 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright (c) 2001 Marcel Moolenaar
  * 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.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
  */
 
 #include <sys/param.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/mutex.h>
 #include <sys/sysctl.h>
 #include <sys/sbuf.h>
 #include <sys/vnode.h>
 
 #ifdef COMPAT_LINUX32
 #include <machine/../linux32/linux.h>
 #include <machine/../linux32/linux32_proto.h>
 #else
 #include <machine/../linux/linux.h>
 #include <machine/../linux/linux_proto.h>
 #endif
 
 #include <compat/linux/linux_dtrace.h>
 #include <compat/linux/linux_misc.h>
 #include <compat/linux/linux_util.h>
 
 #define	LINUX_CTL_KERN		1
 #define	LINUX_CTL_VM		2
 #define	LINUX_CTL_NET		3
 #define	LINUX_CTL_PROC		4
 #define	LINUX_CTL_FS		5
 #define	LINUX_CTL_DEBUG		6
 #define	LINUX_CTL_DEV		7
 #define	LINUX_CTL_BUS		8
 
 /* CTL_KERN names */
 #define	LINUX_KERN_OSTYPE	1
 #define	LINUX_KERN_OSRELEASE	2
 #define	LINUX_KERN_OSREV	3
 #define	LINUX_KERN_VERSION	4
 
 /* DTrace init */
 LIN_SDT_PROVIDER_DECLARE(LINUX_DTRACE);
 
 /**
  * DTrace probes in this module.
  */
 LIN_SDT_PROBE_DEFINE1(sysctl, handle_string, copyout_error, "int");
 LIN_SDT_PROBE_DEFINE1(sysctl, linux_sysctl, copyin_error, "int");
 LIN_SDT_PROBE_DEFINE2(sysctl, linux_sysctl, wrong_length, "int", "int");
 LIN_SDT_PROBE_DEFINE1(sysctl, linux_sysctl, unsupported_sysctl, "char *");
 
 #ifdef LINUX_LEGACY_SYSCALLS
 static int
-handle_string(struct l___sysctl_args *la, char *value)
+handle_string(struct l___sysctl_args *la, const char *value)
 {
 	int error;
 
 	if (la->oldval != 0) {
 		l_int len = strlen(value);
 		error = copyout(value, PTRIN(la->oldval), len + 1);
 		if (!error && la->oldlenp != 0)
 			error = copyout(&len, PTRIN(la->oldlenp), sizeof(len));
 		if (error) {
 			LIN_SDT_PROBE1(sysctl, handle_string, copyout_error,
 			    error);
 			return (error);
 		}
 	}
 
 	if (la->newval != 0)
 		return (ENOTDIR);
 
 	return (0);
 }
 
 int
 linux_sysctl(struct thread *td, struct linux_sysctl_args *args)
 {
 	struct l___sysctl_args la;
 	struct sbuf *sb;
 	l_int *mib;
 	char *sysctl_string;
 	int error, i;
 
 	error = copyin(args->args, &la, sizeof(la));
 	if (error) {
 		LIN_SDT_PROBE1(sysctl, linux_sysctl, copyin_error, error);
 		return (error);
 	}
 
 	if (la.nlen <= 0 || la.nlen > LINUX_CTL_MAXNAME) {
 		LIN_SDT_PROBE2(sysctl, linux_sysctl, wrong_length, la.nlen,
 		    LINUX_CTL_MAXNAME);
 		return (ENOTDIR);
 	}
 
 	mib = malloc(la.nlen * sizeof(l_int), M_LINUX, M_WAITOK);
 	error = copyin(PTRIN(la.name), mib, la.nlen * sizeof(l_int));
 	if (error) {
 		LIN_SDT_PROBE1(sysctl, linux_sysctl, copyin_error, error);
 		free(mib, M_LINUX);
 		return (error);
 	}
 
 	switch (mib[0]) {
 	case LINUX_CTL_KERN:
 		if (la.nlen < 2)
 			break;
 
 		switch (mib[1]) {
 		case LINUX_KERN_VERSION:
 			error = handle_string(&la, version);
 			free(mib, M_LINUX);
 			return (error);
 		default:
 			break;
 		}
 		break;
 	default:
 		break;
 	}
 
 	sb = sbuf_new(NULL, NULL, 20 + la.nlen * 5, SBUF_AUTOEXTEND);
 	if (sb == NULL) {
 		linux_msg(td, "sysctl is not implemented");
 		LIN_SDT_PROBE1(sysctl, linux_sysctl, unsupported_sysctl,
 		    "unknown sysctl, ENOMEM during lookup");
 	} else {
 		sbuf_printf(sb, "sysctl ");
 		for (i = 0; i < la.nlen; i++)
 			sbuf_printf(sb, "%c%d", (i) ? ',' : '{', mib[i]);
 		sbuf_printf(sb, "} is not implemented");
 		sbuf_finish(sb);
 		sysctl_string = sbuf_data(sb);
 		linux_msg(td, "%s", sysctl_string);
 		LIN_SDT_PROBE1(sysctl, linux_sysctl, unsupported_sysctl,
 		    sysctl_string);
 		sbuf_delete(sb);
 	}
 
 	free(mib, M_LINUX);
 
 	return (ENOTDIR);
 }
 #endif