diff --git a/sys/dev/speaker/spkr.c b/sys/dev/speaker/spkr.c
--- a/sys/dev/speaker/spkr.c
+++ b/sys/dev/speaker/spkr.c
@@ -14,6 +14,7 @@
 #include <sys/conf.h>
 #include <sys/ctype.h>
 #include <sys/malloc.h>
+#include <sys/sx.h>
 #include <machine/clock.h>
 #include <dev/speaker/speaker.h>
 
@@ -24,7 +25,6 @@
 
 static struct cdevsw spkr_cdevsw = {
 	.d_version =	D_VERSION,
-	.d_flags =	D_NEEDGIANT,
 	.d_open =	spkropen,
 	.d_close =	spkrclose,
 	.d_write =	spkrwrite,
@@ -392,51 +392,58 @@
 
 static bool spkr_active = false; /* exclusion flag */
 static char *spkr_inbuf;  /* incoming buf */
+static struct sx spkr_lock;
 
 static int
 spkropen(struct cdev *dev, int flags, int fmt, struct thread *td)
 {
+	int error;
+
 #ifdef DEBUG
 	(void) printf("spkropen: entering with dev = %s\n", devtoname(dev));
 #endif /* DEBUG */
 
-	if (spkr_active)
-		return(EBUSY);
-	else {
+	error = 0;
+	sx_xlock(&spkr_lock);
+	if (spkr_active) {
+		error = EBUSY;
+	} else {
 #ifdef DEBUG
 		(void) printf("spkropen: about to perform play initialization\n");
 #endif /* DEBUG */
 		playinit();
 		spkr_inbuf = malloc(DEV_BSIZE, M_SPKR, M_WAITOK);
 		spkr_active = true;
-		return(0);
-    	}
+	}
+	sx_xunlock(&spkr_lock);
+	return (error);
 }
 
 static int
 spkrwrite(struct cdev *dev, struct uio *uio, int ioflag)
 {
+	unsigned n;
+	char *cp;
+	int error;
+
 #ifdef DEBUG
 	printf("spkrwrite: entering with dev = %s, count = %zd\n",
 		devtoname(dev), uio->uio_resid);
 #endif /* DEBUG */
 
 	if (uio->uio_resid > (DEV_BSIZE - 1))     /* prevent system crashes */
-		return(E2BIG);	
-	else {
-		unsigned n;
-		char *cp;
-		int error;
-
-		n = uio->uio_resid;
-		cp = spkr_inbuf;
-		error = uiomove(cp, n, uio);
-		if (!error) {
-			cp[n] = '\0';
-			playstring(cp, n);
-		}
-	return(error);
+		return(E2BIG);
+
+	sx_xlock(&spkr_lock);
+	n = uio->uio_resid;
+	cp = spkr_inbuf;
+	error = uiomove(cp, n, uio);
+	if (!error) {
+		cp[n] = '\0';
+		playstring(cp, n);
 	}
+	sx_xunlock(&spkr_lock);
+	return (error);
 }
 
 static int
@@ -446,10 +453,12 @@
 	(void) printf("spkrclose: entering with dev = %s\n", devtoname(dev));
 #endif /* DEBUG */
 
+	sx_xlock(&spkr_lock);
 	wakeup(&endtone);
 	wakeup(&endrest);
 	free(spkr_inbuf, M_SPKR);
 	spkr_active = false;
+	sx_xunlock(&spkr_lock);
 	return(0);
 }
 
@@ -457,28 +466,30 @@
 spkrioctl(struct cdev *dev, unsigned long cmd, caddr_t cmdarg, int flags,
     struct thread *td)
 {
+	tone_t *tp, ttp;
+	int error;
+
 #ifdef DEBUG
 	(void) printf("spkrioctl: entering with dev = %s, cmd = %lx\n",
     		devtoname(dev), cmd);
 #endif /* DEBUG */
 
+	error = 0;
+	sx_xlock(&spkr_lock);
 	if (cmd == SPKRTONE) {
-		tone_t	*tp = (tone_t *)cmdarg;
+		tp = (tone_t *)cmdarg;
 
 		if (tp->frequency == 0)
 			rest(tp->duration);
 		else
 			tone(tp->frequency, tp->duration);
-		return 0;
 	} else if (cmd == SPKRTUNE) {
-		tone_t  *tp = (tone_t *)(*(caddr_t *)cmdarg);
-		tone_t ttp;
-		int error;
+		tp = (tone_t *)(*(caddr_t *)cmdarg);
 
 		for (; ; tp++) {
 			error = copyin(tp, &ttp, sizeof(tone_t));
 			if (error)
-				return(error);
+				break;
 
 			if (ttp.duration == 0)
 				break;
@@ -488,9 +499,11 @@
 			else
 				tone(ttp.frequency, ttp.duration);
 		}
-		return(0);
+	} else {
+		error = EINVAL;
 	}
-	return(EINVAL);
+	sx_xunlock(&spkr_lock);
+	return (error);
 }
 
 static struct cdev *speaker_dev;
@@ -504,13 +517,15 @@
 	int error = 0;
 
 	switch(type) {
-	case MOD_LOAD: 
+	case MOD_LOAD:
+		sx_init(&spkr_lock, "speaker");
 		speaker_dev = make_dev(&spkr_cdevsw, 0,
 		    UID_ROOT, GID_WHEEL, 0600, "speaker");
 		break;
 	case MOD_SHUTDOWN:
 	case MOD_UNLOAD:
 		destroy_dev(speaker_dev);
+		sx_destroy(&spkr_lock);
 		break;
 	default:
 		error = EOPNOTSUPP;
diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c
--- a/sys/x86/isa/clock.c
+++ b/sys/x86/isa/clock.c
@@ -163,8 +163,11 @@
 
 	mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
 
-	if (timer2_state != RELEASED)
+	mtx_lock_spin(&clock_lock);
+	if (timer2_state != RELEASED) {
+		mtx_unlock_spin(&clock_lock);
 		return (-1);
+	}
 	timer2_state = ACQUIRED;
 
 	/*
@@ -175,6 +178,7 @@
 	 * careful with it as with timer0.
 	 */
 	outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
+	mtx_unlock_spin(&clock_lock);
 
 	ppi_spkr_on();		/* enable counter2 output to speaker */
 	return (0);
@@ -184,10 +188,14 @@
 timer_spkr_release(void)
 {
 
-	if (timer2_state != ACQUIRED)
+	mtx_lock_spin(&clock_lock);
+	if (timer2_state != ACQUIRED) {
+		mtx_unlock_spin(&clock_lock);
 		return (-1);
+	}
 	timer2_state = RELEASED;
 	outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
+	mtx_unlock_spin(&clock_lock);
 
 	ppi_spkr_off();		/* disable counter2 output to speaker */
 	return (0);