diff --git a/usr.bin/config/defs.h b/usr.bin/config/defs.h
index b45d31ff377c..abeb9bb0485d 100644
--- a/usr.bin/config/defs.h
+++ b/usr.bin/config/defs.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: defs.h,v 1.108 2024/01/18 05:41:38 thorpej Exp $	*/
+/*	$NetBSD: defs.h,v 1.109 2024/04/05 00:43:42 riastradh Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -207,6 +207,8 @@ struct attr {
 	/* "device class" */
 	const char *a_devclass;		/* device class described */
 	struct where a_where;
+
+	size_t	a_idx;			/* index to break sorting ties */
 };
 
 /*
diff --git a/usr.bin/config/files.c b/usr.bin/config/files.c
index ae7126d2ee68..6ff47181d569 100644
--- a/usr.bin/config/files.c
+++ b/usr.bin/config/files.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: files.c,v 1.37 2020/03/07 19:26:13 christos Exp $	*/
+/*	$NetBSD: files.c,v 1.38 2024/04/05 00:43:42 riastradh Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -45,7 +45,7 @@
 #endif
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: files.c,v 1.37 2020/03/07 19:26:13 christos Exp $");
+__RCSID("$NetBSD: files.c,v 1.38 2024/04/05 00:43:42 riastradh Exp $");
 
 #include <sys/param.h>
 #include <assert.h>
@@ -281,9 +281,9 @@ cmpfiles(const void *a, const void *b)
 	if (sa < sb)
 		return -1;
 	else if (sa > sb)
-		return 1;
+		return +1;
 	else
-		return 0;
+		abort();	/* no ties possible */
 }
 
 /*
diff --git a/usr.bin/config/mkioconf.c b/usr.bin/config/mkioconf.c
index ae39a55b8613..8ae454228450 100644
--- a/usr.bin/config/mkioconf.c
+++ b/usr.bin/config/mkioconf.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: mkioconf.c,v 1.35 2017/11/19 01:46:29 christos Exp $	*/
+/*	$NetBSD: mkioconf.c,v 1.36 2024/04/05 00:43:42 riastradh Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -45,7 +45,7 @@
 #endif
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: mkioconf.c,v 1.35 2017/11/19 01:46:29 christos Exp $");
+__RCSID("$NetBSD: mkioconf.c,v 1.36 2024/04/05 00:43:42 riastradh Exp $");
 
 #include <sys/param.h>
 #include <err.h>
@@ -136,7 +136,12 @@ cforder(const void *a, const void *b)
 
 	n1 = (*(const struct devi * const *)a)->i_cfindex;
 	n2 = (*(const struct devi * const *)b)->i_cfindex;
-	return (n1 - n2);
+	if (n1 < n2)
+		return -1;
+	else if (n1 > n2)
+		return +1;
+	else
+		abort();	/* no ties possible */
 }
 
 static void
diff --git a/usr.bin/config/mkmakefile.c b/usr.bin/config/mkmakefile.c
index fe5232eaeb57..32ca947c49ae 100644
--- a/usr.bin/config/mkmakefile.c
+++ b/usr.bin/config/mkmakefile.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: mkmakefile.c,v 1.72 2024/01/18 04:41:37 thorpej Exp $	*/
+/*	$NetBSD: mkmakefile.c,v 1.73 2024/04/05 00:43:42 riastradh Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -45,7 +45,7 @@
 #endif
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: mkmakefile.c,v 1.72 2024/01/18 04:41:37 thorpej Exp $");
+__RCSID("$NetBSD: mkmakefile.c,v 1.73 2024/04/05 00:43:42 riastradh Exp $");
 
 #include <sys/param.h>
 #include <ctype.h>
@@ -413,6 +413,7 @@ emitallkobjscb(const char *name, void *v, void *arg)
 		return 0;
 	if (TAILQ_EMPTY(&a->a_files))
 		return 0;
+	a->a_idx = attridx;
 	attrbuf[attridx++] = a;
 	/* XXX nattrs tracking is not exact yet */
 	if (attridx == nattrs) {
@@ -447,7 +448,21 @@ attrcmp(const void *l, const void *r)
 {
 	const struct attr * const *a = l, * const *b = r;
 	const int wa = (*a)->a_weight, wb = (*b)->a_weight;
-	return (wa > wb) ? -1 : (wa < wb) ? 1 : 0;
+
+	/*
+	 * Higher-weight first; then, among equal weights, earlier
+	 * index first.
+	 */
+	if (wa > wb)
+		return -1;
+	else if (wa < wb)
+		return +1;
+	else if ((*a)->a_idx < (*b)->a_idx)
+		return -1;
+	else if ((*a)->a_idx > (*b)->a_idx)
+		return +1;
+	else
+		abort();	/* no ties possible */
 }
 
 static void
diff --git a/usr.bin/config/pack.c b/usr.bin/config/pack.c
index f227aa3b3539..d48edc360eb8 100644
--- a/usr.bin/config/pack.c
+++ b/usr.bin/config/pack.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: pack.c,v 1.10 2015/09/12 19:11:13 joerg Exp $	*/
+/*	$NetBSD: pack.c,v 1.11 2024/04/05 00:43:42 riastradh Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -45,7 +45,7 @@
 #endif
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: pack.c,v 1.10 2015/09/12 19:11:13 joerg Exp $");
+__RCSID("$NetBSD: pack.c,v 1.11 2024/04/05 00:43:42 riastradh Exp $");
 
 #include <sys/param.h>
 #include <stdlib.h>
@@ -319,21 +319,38 @@ addlocs(const char **locs, int len)
 
 /*
  * Comparison function for qsort-by-locator-length, longest first.
- * We rashly assume that subtraction of these lengths does not overflow.
+ *
+ * In the event of equality, break ties by i_cfindex, which should be
+ * unique, obviating the need for a stable sort.
  */
 static int
 loclencmp(const void *a, const void *b)
 {
+	const struct devi *const *d1p = a, *d1 = *d1p;
+	const struct devi *const *d2p = b, *d2 = *d2p;
 	const struct pspec *p1, *p2;
 	int l1, l2;
 
-	p1 = (*(const struct devi * const *)a)->i_pspec;
+	p1 = d1->i_pspec;
 	l1 = p1 != NULL ? p1->p_iattr->a_loclen : 0;
 
-	p2 = (*(const struct devi * const *)b)->i_pspec;
+	p2 = d2->i_pspec;
 	l2 = p2 != NULL ? p2->p_iattr->a_loclen : 0;
 
-	return (l2 - l1);
+	/*
+	 * Longer locators first; among equal locator lengths, earliest
+	 * index first.
+	 */
+	if (l2 < l1)
+		return -1;
+	else if (l2 > l1)
+		return +1;
+	else if (d2->i_cfindex > d1->i_cfindex)
+		return -1;
+	else if (d2->i_cfindex < d1->i_cfindex)
+		return +1;
+	else
+		abort();	/* no ties possible */
 }
 
 static void