diff --git a/include/unistd.h b/include/unistd.h
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -579,7 +579,7 @@
 void	 setusershell(void);
 int	 strtofflags(char **, u_long *, u_long *);
 int	 swapon(const char *);
-int	 swapoff(const char *);
+int	 swapoff(const char *, u_int);
 int	 syscall(int, ...);
 off_t	 __syscall(quad_t, ...);
 int	 undelete(const char *);
diff --git a/lib/libc/include/compat.h b/lib/libc/include/compat.h
--- a/lib/libc/include/compat.h
+++ b/lib/libc/include/compat.h
@@ -69,6 +69,8 @@
 
 __sym_compat(kevent, freebsd11_kevent, FBSD_1.0);
 
+__sym_compat(swapoff, freebsd13_swapoff, FBSD_1.0);
+
 #undef __sym_compat
 
 #define	__weak_reference(sym,alias)	\
diff --git a/lib/libc/sys/Symbol.map b/lib/libc/sys/Symbol.map
--- a/lib/libc/sys/Symbol.map
+++ b/lib/libc/sys/Symbol.map
@@ -260,7 +260,6 @@
 	sigwaitinfo;
 	socket;
 	socketpair;
-	swapoff;
 	swapon;
 	symlink;
 	sync;
@@ -420,6 +419,7 @@
 FBSD_1.7 {
 	_Fork;
 	fspacectl;
+	swapoff;
 };
 
 FBSDprivate_1.0 {
diff --git a/lib/libc/sys/swapon.2 b/lib/libc/sys/swapon.2
--- a/lib/libc/sys/swapon.2
+++ b/lib/libc/sys/swapon.2
@@ -28,7 +28,7 @@
 .\"     @(#)swapon.2	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd December 2, 2021
+.Dd December 8, 2021
 .Dt SWAPON 2
 .Os
 .Sh NAME
@@ -43,7 +43,7 @@
 .Ft int
 .Fn swapon "const char *special"
 .Ft int
-.Fn swapoff "const char *special"
+.Fn swapoff "const char *special" "u_int flags"
 .Sh DESCRIPTION
 The
 .Fn swapon
@@ -68,27 +68,7 @@
 .Pp
 The
 .Fa special
-argument points to either the string that names the special device
-used for swapping or the following structure
-.Bd -literal
-struct swapoff_new_args {
-	const char *name_old_syscall;
-	const char *name;
-	u_int flags;
-};
-.Ed
-that extends swapoff's interface to include optional flags.
-The
-.Va name_old_syscall
-member must be initialized to
-.Dv NULL
-for the system to recognize the extended interface.
-It is recommended that the whole structure be zeroed for future
-compatibility, due to padding.
-.Pp
-The
-.Va name
-string is the special device name, same as legacy syscall argument.
+argument points to the name of the device or file used for swapping.
 .The
 .Va flags
 argument takes the following flags:
diff --git a/sbin/swapon/swapon.c b/sbin/swapon/swapon.c
--- a/sbin/swapon/swapon.c
+++ b/sbin/swapon/swapon.c
@@ -789,18 +789,12 @@
 static const char *
 swap_on_off_sfile(const char *name, int doingall)
 {
-	struct swapoff_new_args sa;
 	int error;
 
 	if (which_prog == SWAPON)
 		error = Eflag ? swapon_trim(name) : swapon(name);
-	else { /* SWAPOFF */
-		bzero(&sa, sizeof(sa));
-		sa.name = name;
-		if (fflag)
-			sa.flags |= SWAPOFF_FORCE;
-		error = swapoff((const char *)&sa);
-	}
+	else /* SWAPOFF */
+		error = swapoff(name, fflag ? SWAPOFF_FORCE : 0);
 
 	if (error == -1) {
 		switch (errno) {
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -34,6 +34,7 @@
 ;	COMPAT10 included on COMPAT_FREEBSD10 #ifdef (FreeBSD 10 compat)
 ;	COMPAT11 included on COMPAT_FREEBSD11 #ifdef (FreeBSD 11 compat)
 ;	COMPAT12 included on COMPAT_FREEBSD12 #ifdef (FreeBSD 12 compat)
+;	COMPAT13 included on COMPAT_FREEBSD13 #ifdef (FreeBSD 13 compat)
 ;	OBSOL	obsolete, not included in system, only specifies name
 ;	RESERVED reserved for local or vendor use (not for FreeBSD)
 ;	UNIMPL	not implemented, placeholder only
@@ -2246,7 +2247,7 @@
 		    _In_ _Contains_long_ptr_ const struct __ucontext *ucp
 		);
 	}
-424	AUE_SWAPOFF	STD {
+424	AUE_SWAPOFF	COMPAT13 {
 		int swapoff(
 		    _In_z_ const char *name
 		);
@@ -3299,6 +3300,13 @@
 		int sched_getcpu(void);
 	}
 
+582	AUE_SWAPOFF	STD {
+		int swapoff(
+		    _In_z_ const char *name,
+		    u_int flags,
+		);
+	}
+
 ; Please copy any additions and changes to the following compatability tables:
 ; sys/compat/freebsd32/syscalls.master
 ; vim: syntax=off
diff --git a/sys/sys/unistd.h b/sys/sys/unistd.h
--- a/sys/sys/unistd.h
+++ b/sys/sys/unistd.h
@@ -198,6 +198,8 @@
     RFPROCDESC | RFSPAWN | RFPPWAIT)
 #define	RFKERNELONLY	(RFSTOPPED | RFHIGHPID | RFPROCDESC)
 
+#define	SWAPOFF_FORCE	0x00000001
+
 #endif /* __BSD_VISIBLE */
 
 #endif /* !_SYS_UNISTD_H_ */
diff --git a/sys/tools/makesyscalls.lua b/sys/tools/makesyscalls.lua
--- a/sys/tools/makesyscalls.lua
+++ b/sys/tools/makesyscalls.lua
@@ -226,6 +226,7 @@
 	{ stdcompat = "FREEBSD10" },
 	{ stdcompat = "FREEBSD11" },
 	{ stdcompat = "FREEBSD12" },
+	{ stdcompat = "FREEBSD13" },
 }
 
 local function trim(s, char)
diff --git a/sys/vm/swap_pager.h b/sys/vm/swap_pager.h
--- a/sys/vm/swap_pager.h
+++ b/sys/vm/swap_pager.h
@@ -69,16 +69,6 @@
 #define	SW_UNMAPPED	0x01
 #define	SW_CLOSING	0x04
 
-struct swapoff_new_args {
-	const char *name_old_syscall;
-	const char *name;
-	u_int flags;
-	u_int pad0;
-	uintptr_t pad1[8];
-};
-
-#define	SWAPOFF_FORCE	0x00000001
-
 #ifdef _KERNEL
 
 extern int swap_pager_avail;
diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -100,6 +100,7 @@
 #include <sys/sysproto.h>
 #include <sys/systm.h>
 #include <sys/sx.h>
+#include <sys/unistd.h>
 #include <sys/user.h>
 #include <sys/vmmeter.h>
 #include <sys/vnode.h>
@@ -2479,50 +2480,24 @@
  * rather than filename as specification.  We keep sw_vp around
  * only to make this work.
  */
-#ifndef _SYS_SYSPROTO_H_
-struct swapoff_args {
-	char *name;
-};
-#endif
-
-int
-sys_swapoff(struct thread *td, struct swapoff_args *uap)
+static int
+kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg,
+    u_int flags)
 {
 	struct vnode *vp;
 	struct nameidata nd;
 	struct swdevt *sp;
-	struct swapoff_new_args sa;
-	int error, probe_byte;
+	int error;
 
 	error = priv_check(td, PRIV_SWAPOFF);
-	if (error)
+	if (error != 0)
 		return (error);
-
-	/*
-	 * Detect old vs. new-style swapoff(2) syscall.  The first
-	 * pointer in the memory pointed to by uap->name is NULL for
-	 * the new variant.
-	 */
-	probe_byte = fubyte(uap->name);
-	switch (probe_byte) {
-	case -1:
-		return (EFAULT);
-	case 0:
-		error = copyin(uap->name, &sa, sizeof(sa));
-		if (error != 0)
-			return (error);
-		if ((sa.flags & ~(SWAPOFF_FORCE)) != 0)
-			return (EINVAL);
-		break;
-	default:
-		bzero(&sa, sizeof(sa));
-		sa.name = uap->name;
-		break;
-	}
+	if ((flags & ~(SWAPOFF_FORCE)) != 0)
+		return (EINVAL);
 
 	sx_xlock(&swdev_syscall_lock);
 
-	NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, sa.name);
+	NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name);
 	error = namei(&nd);
 	if (error)
 		goto done;
@@ -2539,12 +2514,27 @@
 		error = EINVAL;
 		goto done;
 	}
-	error = swapoff_one(sp, td->td_ucred, sa.flags);
+	error = swapoff_one(sp, td->td_ucred, flags);
 done:
 	sx_xunlock(&swdev_syscall_lock);
 	return (error);
 }
 
+
+#ifdef COMPAT_FREEBSD13
+int
+freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap)
+{
+	return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0));
+}
+#endif
+
+int
+sys_swapoff(struct thread *td, struct swapoff_args *uap)
+{
+	return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags));
+}
+
 static int
 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags)
 {
diff --git a/tests/sys/audit/administrative.c b/tests/sys/audit/administrative.c
--- a/tests/sys/audit/administrative.c
+++ b/tests/sys/audit/administrative.c
@@ -1605,7 +1605,7 @@
 
 	FILE *pipefd = setup(fds, auclass);
 	/* Failure reason: Block device required */
-	ATF_REQUIRE_EQ(-1, swapoff(path));
+	ATF_REQUIRE_EQ(-1, swapoff(path, 0));
 	check_audit(fds, adregex, pipefd);
 }