Index: head/sys/compat/linux/linux_misc.c
===================================================================
--- head/sys/compat/linux/linux_misc.c
+++ head/sys/compat/linux/linux_misc.c
@@ -232,22 +232,18 @@
 linux_brk(struct thread *td, struct linux_brk_args *args)
 {
 	struct vmspace *vm = td->td_proc->p_vmspace;
-	vm_offset_t new, old;
-	struct break_args /* {
-		char * nsize;
-	} */ tmp;
+	uintptr_t new, old;
 
 #ifdef DEBUG
 	if (ldebug(brk))
 		printf(ARGS(brk, "%p"), (void *)(uintptr_t)args->dsend);
 #endif
-	old = (vm_offset_t)vm->vm_daddr + ctob(vm->vm_dsize);
-	new = (vm_offset_t)args->dsend;
-	tmp.nsize = (char *)new;
-	if (((caddr_t)new > vm->vm_daddr) && !sys_break(td, &tmp))
-		td->td_retval[0] = (long)new;
+	old = (uintptr_t)vm->vm_daddr + ctob(vm->vm_dsize);
+	new = (uintptr_t)args->dsend;
+	if ((caddr_t)new > vm->vm_daddr && !kern_break(td, &new))
+		td->td_retval[0] = (register_t)new;
 	else
-		td->td_retval[0] = (long)old;
+		td->td_retval[0] = (register_t)old;
 
 	return (0);
 }
Index: head/sys/sys/syscallsubr.h
===================================================================
--- head/sys/sys/syscallsubr.h
+++ head/sys/sys/syscallsubr.h
@@ -76,6 +76,7 @@
 int	kern_alternate_path(struct thread *td, const char *prefix, const char *path,
 	    enum uio_seg pathseg, char **pathbuf, int create, int dirfd);
 int	kern_bindat(struct thread *td, int dirfd, int fd, struct sockaddr *sa);
+int	kern_break(struct thread *td, uintptr_t *addr);
 int	kern_cap_ioctls_limit(struct thread *td, int fd, u_long *cmds,
 	    size_t ncmds);
 int	kern_cap_rights_limit(struct thread *td, int fd, cap_rights_t *rights);
Index: head/sys/vm/vm_unix.c
===================================================================
--- head/sys/vm/vm_unix.c
+++ head/sys/vm/vm_unix.c
@@ -51,6 +51,7 @@
 #include <sys/proc.h>
 #include <sys/racct.h>
 #include <sys/resourcevar.h>
+#include <sys/syscallsubr.h>
 #include <sys/sysent.h>
 #include <sys/sysproto.h>
 #include <sys/systm.h>
@@ -69,6 +70,22 @@
 sys_break(struct thread *td, struct break_args *uap)
 {
 #if !defined(__aarch64__) && !defined(__riscv__)
+	uintptr_t addr;
+	int error;
+
+	addr = (uintptr_t)uap->nsize;
+	error = kern_break(td, &addr);
+	if (error == 0)
+		td->td_retval[0] = addr;
+	return (error);
+#else /* defined(__aarch64__) || defined(__riscv__) */
+	return (ENOSYS);
+#endif /* defined(__aarch64__) || defined(__riscv__) */
+}
+
+int
+kern_break(struct thread *td, uintptr_t *addr)
+{
 	struct vmspace *vm = td->td_proc->p_vmspace;
 	vm_map_t map = &vm->vm_map;
 	vm_offset_t new, old, base;
@@ -82,7 +99,7 @@
 	vmemlim = lim_cur(td, RLIMIT_VMEM);
 
 	do_map_wirefuture = FALSE;
-	new = round_page((vm_offset_t)uap->nsize);
+	new = round_page(*addr);
 	vm_map_lock(map);
 
 	base = round_page((vm_offset_t) vm->vm_daddr);
@@ -226,12 +243,9 @@
 		    VM_MAP_WIRE_USER|VM_MAP_WIRE_NOHOLES);
 
 	if (error == 0)
-		td->td_retval[0] = new;
+		*addr = new;
 
 	return (error);
-#else /* defined(__aarch64__) || defined(__riscv__) */
-	return (ENOSYS);
-#endif /* defined(__aarch64__) || defined(__riscv__) */
 }
 
 #ifdef COMPAT_FREEBSD11