diff --git a/usr.bin/cdplay/cdplay.c b/usr.bin/cdplay/cdplay.c
index 69f869e2d63d..7f51ab2cf0da 100644
--- a/usr.bin/cdplay/cdplay.c
+++ b/usr.bin/cdplay/cdplay.c
@@ -1,4 +1,4 @@
-/* 	$NetBSD: cdplay.c,v 1.50 2020/10/18 21:58:32 rillig Exp $	*/
+/* 	$NetBSD: cdplay.c,v 1.51 2021/11/27 22:16:41 rillig Exp $	*/
 
 /*
  * Copyright (c) 1999, 2000, 2001 Andrew Doran.
@@ -40,7 +40,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: cdplay.c,v 1.50 2020/10/18 21:58:32 rillig Exp $");
+__RCSID("$NetBSD: cdplay.c,v 1.51 2021/11/27 22:16:41 rillig Exp $");
 #endif /* not lint */
 
 #include <sys/types.h>
@@ -130,7 +130,7 @@ static struct cmdtab {
 			fd = -1;		\
 		} else				\
 			warn("ioctl(" #ctl ")");\
-	} while (/* CONSTCOND */ 0)
+	} while (0)
 
 #define CDDA_SIZE	2352
 
diff --git a/usr.bin/fdformat/fdformat.c b/usr.bin/fdformat/fdformat.c
index 4fb8835cafdb..54f748ef1457 100644
--- a/usr.bin/fdformat/fdformat.c
+++ b/usr.bin/fdformat/fdformat.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: fdformat.c,v 1.17 2016/09/05 00:40:28 sevan Exp $	*/
+/*	$NetBSD: fdformat.c,v 1.18 2021/11/27 22:16:41 rillig Exp $	*/
 
 /*-
  * Copyright (c) 1996, 1997 The NetBSD Foundation, Inc.
@@ -36,7 +36,7 @@
 #include <sys/cdefs.h>
 
 #ifndef lint
-__RCSID("$NetBSD: fdformat.c,v 1.17 2016/09/05 00:40:28 sevan Exp $");
+__RCSID("$NetBSD: fdformat.c,v 1.18 2021/11/27 22:16:41 rillig Exp $");
 #endif
 
 #include <sys/types.h>
@@ -135,7 +135,7 @@ usage(void)
 			# which, optarg); 			\
 		parms.which = tmplong; 				\
 		parmmask |= MASK_##maskn;			\
-	} while (/* CONSTCOND */0)
+	} while (0)
 
 #define getparm(structname, maskname) 				\
 	do {							\
@@ -144,7 +144,7 @@ usage(void)
 			    " missing for type `%s'", optarg);	\
 		parms.structname = tmplong; 			\
 		parmmask |= MASK_ ## maskname;			\
-	} while (/* CONSTCOND */0)
+	} while (0)
 
 
 #define copyparm(which, mask) 					\
diff --git a/usr.bin/mail/sig.c b/usr.bin/mail/sig.c
index af7148a05add..de7086218dff 100644
--- a/usr.bin/mail/sig.c
+++ b/usr.bin/mail/sig.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: sig.c,v 1.3 2012/06/12 19:03:26 christos Exp $	*/
+/*	$NetBSD: sig.c,v 1.4 2021/11/27 22:16:41 rillig Exp $	*/
 
 /*
  * Copyright (c) 1980, 1993
@@ -31,7 +31,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: sig.c,v 1.3 2012/06/12 19:03:26 christos Exp $");
+__RCSID("$NetBSD: sig.c,v 1.4 2021/11/27 22:16:41 rillig Exp $");
 #endif /* not lint */
 
 #include <assert.h>
@@ -63,7 +63,7 @@ static struct {
 #define SIGQUEUE_INIT(p)  do {\
 	(p)->qe_first = NULL;\
 	(p)->qe_last = &((p)->qe_first);\
-  } while (/*CONSTCOND*/ 0)
+  } while (0)
 
 /*
  * The routines alloc_entry() and free_entry() manage the queue
diff --git a/usr.bin/midiplay/midiplay.c b/usr.bin/midiplay/midiplay.c
index dc8607c97c5c..a7a77d5a1079 100644
--- a/usr.bin/midiplay/midiplay.c
+++ b/usr.bin/midiplay/midiplay.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: midiplay.c,v 1.33 2019/02/01 08:37:21 mrg Exp $	*/
+/*	$NetBSD: midiplay.c,v 1.34 2021/11/27 22:16:41 rillig Exp $	*/
 
 /*
  * Copyright (c) 1998, 2002 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
 #include <sys/cdefs.h>
 
 #ifndef lint
-__RCSID("$NetBSD: midiplay.c,v 1.33 2019/02/01 08:37:21 mrg Exp $");
+__RCSID("$NetBSD: midiplay.c,v 1.34 2021/11/27 22:16:41 rillig Exp $");
 #endif
 
 
@@ -842,7 +842,7 @@ main(int argc, char **argv)
     struct track *_t = t[i].indirect; \
     t[i].indirect = t[j].indirect; \
     t[j].indirect = _t; \
-} while (/*CONSTCOND*/ 0)
+} while (0)
 
 static void
 Heapify(struct track *t, int ntrks, int node)
diff --git a/usr.bin/su/su_pam.c b/usr.bin/su/su_pam.c
index 8e6bfeb886fe..8473f8e8aa5e 100644
--- a/usr.bin/su/su_pam.c
+++ b/usr.bin/su/su_pam.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: su_pam.c,v 1.22 2021/09/10 21:52:18 rillig Exp $	*/
+/*	$NetBSD: su_pam.c,v 1.23 2021/11/27 22:16:42 rillig Exp $	*/
 
 /*
  * Copyright (c) 1988 The Regents of the University of California.
@@ -39,7 +39,7 @@ __COPYRIGHT("@(#) Copyright (c) 1988\
 #if 0
 static char sccsid[] = "@(#)su.c	8.3 (Berkeley) 4/2/94";*/
 #else
-__RCSID("$NetBSD: su_pam.c,v 1.22 2021/09/10 21:52:18 rillig Exp $");
+__RCSID("$NetBSD: su_pam.c,v 1.23 2021/11/27 22:16:42 rillig Exp $");
 #endif
 #endif /* not lint */
 
@@ -293,12 +293,12 @@ main(int argc, char **argv)
 #define ERRX_PAM_END(args) do {			\
 	(void)pam_end(pamh, pam_err);		\
 	errx args;				\
-} while (/* CONSTCOND */0)
+} while (0)
 
 #define ERR_PAM_END(args) do {			\
 	(void)pam_end(pamh, pam_err);		\
 	err args;				\
-} while (/* CONSTCOND */0)
+} while (0)
 
 	/* force the usage of specified class */
 	if (class) {
diff --git a/usr.bin/vmstat/drvstats.c b/usr.bin/vmstat/drvstats.c
index effcb84c1893..6c09e6b5bc29 100644
--- a/usr.bin/vmstat/drvstats.c
+++ b/usr.bin/vmstat/drvstats.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: drvstats.c,v 1.13 2019/06/30 19:57:24 he Exp $	*/
+/*	$NetBSD: drvstats.c,v 1.14 2021/11/27 22:16:42 rillig Exp $	*/
 
 /*
  * Copyright (c) 1996 John M. Vinopal
@@ -64,7 +64,7 @@ char		**dr_name;
 #define	timerset(tvp, uvp) do {						\
 	((uvp)->tv_sec = (tvp)->tv_sec);				\
 	((uvp)->tv_usec = (tvp)->tv_usec);				\
-} while (/* CONSTCOND */0)
+} while (0)
 
 /*
  * Take the delta between the present values and the last recorded
@@ -81,7 +81,7 @@ drvswap(void)
 	tmp = cur.fld;							\
 	cur.fld -= last.fld;						\
 	last.fld = tmp;							\
-} while (/* CONSTCOND */0)
+} while (0)
 
 #define DELTA(x) do {							\
 		timerclear(&tmp_timer);					\
@@ -89,7 +89,7 @@ drvswap(void)
 		timersub(&tmp_timer, &(last.x), &(cur.x));		\
 		timerclear(&(last.x));					\
 		timerset(&tmp_timer, &(last.x));			\
-} while (/* CONSTCOND */0)
+} while (0)
 
 	for (i = 0; i < ndrive; i++) {
 		struct timeval	tmp_timer;
@@ -194,7 +194,7 @@ drvreadstats(void)
 #define COPYT(x,k,l) do {						\
 		cur.x[k].tv_sec = drives[l].x##_sec;			\
 		cur.x[k].tv_usec = drives[l].x##_usec;			\
-} while (/* CONSTCOND */0)
+} while (0)
 
 	for (i = 0, j = 0; i < ndrive && j < count; i++) {
 
diff --git a/usr.bin/vmstat/vmstat.c b/usr.bin/vmstat/vmstat.c
index 29512d614002..58ed326a667d 100644
--- a/usr.bin/vmstat/vmstat.c
+++ b/usr.bin/vmstat/vmstat.c
@@ -1,4 +1,4 @@
-/* $NetBSD: vmstat.c,v 1.247 2021/08/22 22:24:12 rillig Exp $ */
+/* $NetBSD: vmstat.c,v 1.248 2021/11/27 22:16:42 rillig Exp $ */
 
 /*-
  * Copyright (c) 1998, 2000, 2001, 2007, 2019, 2020
@@ -71,7 +71,7 @@ __COPYRIGHT("@(#) Copyright (c) 1980, 1986, 1991, 1993\
 #if 0
 static char sccsid[] = "@(#)vmstat.c	8.2 (Berkeley) 3/1/95";
 #else
-__RCSID("$NetBSD: vmstat.c,v 1.247 2021/08/22 22:24:12 rillig Exp $");
+__RCSID("$NetBSD: vmstat.c,v 1.248 2021/11/27 22:16:42 rillig Exp $");
 #endif
 #endif /* not lint */
 
@@ -285,7 +285,7 @@ kvm_t *kd;
 	    (val)) - (width);				\
 	if ((ovflw) < 0)				\
 		(ovflw) = 0;				\
-} while (/* CONSTCOND */0)
+} while (0)
 
 void	cpustats(int *);
 void	cpucounters(struct cpu_counter *);
@@ -1372,7 +1372,7 @@ doevcnt(int verbose, int type)
 			    (int)total_max, counttotal,
 			    (int)rate_max, counttotal / uptime);
 		return;
-	} while (/*CONSTCOND*/ 0);
+	} while (0);
 
 	if (type == EVCNT_TYPE_ANY)
 		(void)printf("%-34s %16s %8s %s\n", "event", "total", "rate",