diff --git a/sys/dev/sound/dummy.c b/sys/dev/sound/dummy.c
--- a/sys/dev/sound/dummy.c
+++ b/sys/dev/sound/dummy.c
@@ -74,8 +74,6 @@
 	struct dummy_chan *ch;
 	int i = 0;
 
-	snd_mtxlock(sc->lock);
-
 	for (i = 0; i < sc->chnum; i++) {
 		ch = &sc->chans[i];
 		if (!ch->run)
@@ -89,8 +87,6 @@
 		snd_mtxlock(sc->lock);
 	}
 	callout_schedule(&sc->callout, 1);
-
-	snd_mtxunlock(sc->lock);
 }
 
 static int
@@ -179,16 +175,14 @@
 
 	switch (go) {
 	case PCMTRIG_START:
-		if (!callout_active(&sc->callout))
-			callout_reset(&sc->callout, 1, dummy_chan_io, sc);
+		callout_reset(&sc->callout, 1, dummy_chan_io, sc);
 		ch->ptr = 0;
 		ch->run = 1;
 		break;
 	case PCMTRIG_STOP:
 	case PCMTRIG_ABORT:
 		ch->run = 0;
-		if (callout_active(&sc->callout))
-			callout_stop(&sc->callout);
+		callout_stop(&sc->callout);
 	default:
 		break;
 	}
@@ -292,6 +286,7 @@
 	sc = device_get_softc(dev);
 	sc->dev = dev;
 	sc->lock = snd_mtxcreate(device_get_nameunit(dev), "snd_dummy softc");
+	callout_init_mtx(&sc->callout, sc->lock, 0);
 
 	sc->cap_fmts[0] = SND_FORMAT(AFMT_S32_LE, 2, 0);
 	sc->cap_fmts[1] = SND_FORMAT(AFMT_S24_LE, 2, 0);
@@ -316,7 +311,6 @@
 	if (pcm_register(dev, status))
 		return (ENXIO);
 	mixer_init(dev, &dummy_mixer_class, sc);
-	callout_init(&sc->callout, 1);
 
 	return (0);
 }
@@ -327,8 +321,11 @@
 	struct dummy_softc *sc = device_get_softc(dev);
 	int err;
 
-	callout_drain(&sc->callout);
 	err = pcm_unregister(dev);
+	snd_mtxlock(sc->lock);
+	callout_stop(&sc->callout);
+	snd_mtxunlock(sc->lock);
+	callout_drain(&sc->callout);
 	snd_mtxfree(sc->lock);
 
 	return (err);