diff --git a/sys/dev/sound/pcm/channel.c b/sys/dev/sound/pcm/channel.c
--- a/sys/dev/sound/pcm/channel.c
+++ b/sys/dev/sound/pcm/channel.c
@@ -1157,6 +1157,24 @@
 	return r;
 }
 
+static struct unrhdr *
+chn_getunr(struct snddev_info *d, int type)
+{
+	switch (type) {
+	case SND_DEV_DSPHW_PLAY:
+		return (d->p_unr);
+	case SND_DEV_DSPHW_VPLAY:
+		return (d->vp_unr);
+	case SND_DEV_DSPHW_REC:
+		return (d->r_unr);
+	case SND_DEV_DSPHW_VREC:
+		return (d->vr_unr);
+	default:
+		__assert_unreachable();
+	}
+
+}
+
 struct pcm_channel *
 chn_init(struct snddev_info *d, struct pcm_channel *parent, kobj_class_t cls,
     int dir, void *devinfo)
@@ -1165,7 +1183,7 @@
 	struct feeder_class *fc;
 	struct snd_dbuf *b, *bs;
 	char *dirs, buf[CHN_NAMELEN];
-	int i, direction, type, unit;
+	int i, direction, type;
 
 	PCM_BUSYASSERT(d);
 	PCM_LOCKASSERT(d);
@@ -1198,13 +1216,6 @@
 		return (NULL);
 	}
 
-	unit = 0;
-	CHN_FOREACH(c, d, channels.pcm) {
-		if (c->type != type)
-			continue;
-		unit++;
-	}
-
 	PCM_UNLOCK(d);
 	b = NULL;
 	bs = NULL;
@@ -1216,7 +1227,7 @@
 	CHN_INIT(c, children.busy);
 	c->direction = direction;
 	c->type = type;
-	c->unit = unit;
+	c->unit = alloc_unr(chn_getunr(d, c->type));
 	c->format = SND_FORMAT(AFMT_U8, 1, 0);
 	c->speed = DSP_DEFAULT_SPEED;
 	c->pid = -1;
@@ -1304,6 +1315,7 @@
 	return (c);
 
 fail:
+	free_unr(chn_getunr(d, c->type), c->unit);
 	feeder_remove(c);
 	if (c->devinfo && CHANNEL_FREE(c->methods, c->devinfo))
 		sndbuf_free(b);
@@ -1335,6 +1347,7 @@
 		chn_trigger(c, PCMTRIG_ABORT);
 		CHN_UNLOCK(c);
 	}
+	free_unr(chn_getunr(c->parentsnddev, c->type), c->unit);
 	feeder_remove(c);
 	if (CHANNEL_FREE(c->methods, c->devinfo))
 		sndbuf_free(b);
diff --git a/sys/dev/sound/pcm/sound.h b/sys/dev/sound/pcm/sound.h
--- a/sys/dev/sound/pcm/sound.h
+++ b/sys/dev/sound/pcm/sound.h
@@ -325,6 +325,10 @@
 	struct sysctl_ctx_list play_sysctl_ctx, rec_sysctl_ctx;
 	struct sysctl_oid *play_sysctl_tree, *rec_sysctl_tree;
 	struct cv cv;
+	struct unrhdr *p_unr;
+	struct unrhdr *vp_unr;
+	struct unrhdr *r_unr;
+	struct unrhdr *vr_unr;
 };
 
 void	sound_oss_sysinfo(oss_sysinfo *);
diff --git a/sys/dev/sound/pcm/sound.c b/sys/dev/sound/pcm/sound.c
--- a/sys/dev/sound/pcm/sound.c
+++ b/sys/dev/sound/pcm/sound.c
@@ -568,6 +568,10 @@
 	d->pvchanformat = 0;
 	d->rvchanrate = 0;
 	d->rvchanformat = 0;
+	d->p_unr = new_unrhdr(0, INT_MAX, NULL);
+	d->vp_unr = new_unrhdr(0, INT_MAX, NULL);
+	d->r_unr = new_unrhdr(0, INT_MAX, NULL);
+	d->vr_unr = new_unrhdr(0, INT_MAX, NULL);
 
 	CHN_INIT(d, channels.pcm);
 	CHN_INIT(d, channels.pcm.busy);
@@ -653,6 +657,14 @@
 	cv_destroy(&d->cv);
 	PCM_UNLOCK(d);
 	snd_mtxfree(d->lock);
+	if (d->p_unr != NULL)
+		delete_unrhdr(d->p_unr);
+	if (d->vp_unr != NULL)
+		delete_unrhdr(d->vp_unr);
+	if (d->r_unr != NULL)
+		delete_unrhdr(d->r_unr);
+	if (d->vr_unr != NULL)
+		delete_unrhdr(d->vr_unr);
 
 	if (snd_unit == device_get_unit(dev)) {
 		snd_unit = pcm_best_unit(-1);