diff --git a/bin/nproc/nproc.1 b/bin/nproc/nproc.1
index 91a87b1ca048..8ebe94a21049 100644
--- a/bin/nproc/nproc.1
+++ b/bin/nproc/nproc.1
@@ -1,55 +1,60 @@
 .\"-
 .\" * Copyright (c) 2023 Piotr Paweł Stefaniak
 .\"
 .\" * SPDX-License-Identifier: BSD-2-Clause
 .\"
-.Dd February 5, 2023
+.Dd February 15, 2023
 .Dt NPROC 1
 .Os
 .Sh NAME
 .Nm nproc
 .Nd print the number of processors
 .Sh SYNOPSIS
 .Nm
 .Op Fl -all
 .Op Fl -ignore Ns = Ns Ar count
 .Nm Fl -help
 .Nm Fl -version
 .Sh DESCRIPTION
 The
 .Nm
 utility is used to print the number of processors limited to the
 .Xr cpuset 2
 of the current process, unless the
 .Fl -all
 flag is specified.
 .Pp
 The available flags are:
 .Bl -tag -width Ds
 .It Fl -all
 Count all processors currently online.
 .It Fl -ignore Ns = Ns Ar count
 The result is decreased by
 .Ar count ,
 but never below 1.
 .It Fl -version
 Print the current program version and exit.
 Do not use this option.
 .It Fl -help
 Print usage information and exit.
 .El
 .Sh COMPATIBILITY
 This program is intended to be compatible with nproc as found in GNU coreutils.
+.Sh BUGS
+If HyperThreading is enabled in BIOS and disabled in the kernel, the
+.Fl -all
+option on Linux will still report all possible CPU threads.
+On FreeBSD only active threads will be reported.
 .Sh SEE ALSO
 .Xr cpuset 1
 .Sh HISTORY
 The
 .Nm
 utility first appeared in
 .Fx 14.0 .
 .Sh AUTHORS
 .An -nosplit
 .An Mateusz Guzik Aq Mt mjg@FreeBSD.org
 wrote the program and
 .An Piotr Paweł Stefaniak Aq Mt pstef@FreeBSD.org
 wrote this page.
diff --git a/bin/nproc/nproc.c b/bin/nproc/nproc.c
index 9037c74dbfff..c2ab75826ce1 100644
--- a/bin/nproc/nproc.c
+++ b/bin/nproc/nproc.c
@@ -1,132 +1,132 @@
 /*-
  * Copyright (c) 2023 Mateusz Guzik
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 /*
  * This program is intended to be compatible with nproc as found in GNU
  * coreutils.
  *
  * In order to maintain that, do not add any features here if they are not
  * present in said program.  If you are looking for anything more advanced you
  * probably should patch cpuset(1) instead.
  */
 
 #include <sys/param.h>
 #include <sys/cpuset.h>
 
 #include <err.h>
 #include <errno.h>
 #include <getopt.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sysexits.h>
 #include <unistd.h>
 
 #define OPT_ALL		(CHAR_MAX + 1)
 #define OPT_IGNORE	(CHAR_MAX + 2)
 #define OPT_VERSION	(CHAR_MAX + 3)
 #define OPT_HELP	(CHAR_MAX + 4)
 
 static struct option long_opts[] = {
 	{ "all", no_argument, NULL, OPT_ALL },
 	{ "ignore", required_argument, NULL, OPT_IGNORE },
 	{ "version", no_argument, NULL, OPT_VERSION },
 	{ "help", no_argument, NULL, OPT_HELP },
 	{ NULL, 0, NULL, 0 }
 };
 
 static void
 help(void)
 {
 	fprintf(stderr,
     "usage: nproc [--all] [--ignore=count]\n");
 	fprintf(stderr,
     "       nproc --help\n");
 	fprintf(stderr,
     "       nproc --version\n");
 }
 
 static void
 usage(void)
 {
 	help();
 	exit(EX_USAGE);
 }
 
 /*
  * GNU variant ships with the --version switch.
  *
  * While we don't have anything to put there, print something which is
  * whitespace-compatible with the original. Version number was taken
  * from coreutils this code is in sync with.
  */
 static void
 version(void)
 {
 	printf("nproc (neither_GNU nor_coreutils) 8.32\n");
 	exit(EXIT_SUCCESS);
 }
 
 int
 main(int argc, char *argv[])
 {
 	const char *errstr;
 	cpuset_t mask;
 	int ch, cpus, ignore;
 	bool all_flag;
 
 	ignore = 0;
 	all_flag = false;
 
 	while ((ch = getopt_long(argc, argv, "", long_opts, NULL)) != -1) {
 		switch (ch) {
 		case OPT_ALL:
 			all_flag = true;
 			break;
 		case OPT_IGNORE:
 			ignore = strtonum(optarg, 0, INT_MAX, &errstr);
 			if (errstr)
 				errx(1, "bad ignore count: %s", errstr);
 			break;
 		case OPT_VERSION:
 			version();
 			__builtin_unreachable();
 		case OPT_HELP:
 			help();
 			exit(EXIT_SUCCESS);
 		default:
 			usage();
 		}
 	}
 
 	argc -= optind;
 	argv += optind;
 
 	if (argc != 0)
 		usage();
 
 	if (all_flag) {
-		cpus = sysconf(_SC_NPROCESSORS_ONLN);
+		cpus = sysconf(_SC_NPROCESSORS_CONF);
 		if (cpus == -1)
 			err(1, "sysconf");
 	} else {
 		CPU_ZERO(&mask);
 		if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1,
 		    sizeof(mask), &mask) != 0)
 			err(1, "cpuset_getaffinity");
 		cpus = CPU_COUNT(&mask);
 	}
 
 	if (ignore >= cpus)
 		cpus = 1;
 	else
 		cpus -= ignore;
 
 	printf("%u\n", cpus);
 
 	exit(EXIT_SUCCESS);
 }