diff --git a/sys/kern/kern_condvar.c b/sys/kern/kern_condvar.c
index 859001be5385..6129c12320a7 100644
--- a/sys/kern/kern_condvar.c
+++ b/sys/kern/kern_condvar.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: kern_condvar.c,v 1.9 2007/07/09 21:10:51 ad Exp $	*/
+/*	$NetBSD: kern_condvar.c,v 1.10 2007/08/01 20:30:38 ad Exp $	*/
 
 /*-
  * Copyright (c) 2006, 2007 The NetBSD Foundation, Inc.
@@ -45,7 +45,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_condvar.c,v 1.9 2007/07/09 21:10:51 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_condvar.c,v 1.10 2007/08/01 20:30:38 ad Exp $");
 
 #include <sys/param.h>
 #include <sys/proc.h>
@@ -57,7 +57,7 @@ __KERNEL_RCSID(0, "$NetBSD: kern_condvar.c,v 1.9 2007/07/09 21:10:51 ad Exp $");
 static void	cv_unsleep(lwp_t *);
 static void	cv_changepri(lwp_t *, pri_t);
 
-syncobj_t cv_syncobj = {
+static syncobj_t cv_syncobj = {
 	SOBJ_SLEEPQ_SORTED,
 	cv_unsleep,
 	cv_changepri,
@@ -65,6 +65,8 @@ syncobj_t cv_syncobj = {
 	syncobj_noowner,
 };
 
+static const char deadcv[] = "deadcv";
+
 /*
  * cv_init:
  *
@@ -90,8 +92,9 @@ cv_destroy(kcondvar_t *cv)
 {
 
 #ifdef DIAGNOSTIC
-	KASSERT(cv->cv_waiters == 0 && cv->cv_wmesg != NULL);
-	cv->cv_wmesg = NULL;
+	KASSERT(cv->cv_wmesg != deadcv && cv->cv_wmesg != NULL);
+	KASSERT(cv->cv_waiters == 0);
+	cv->cv_wmesg = deadcv;
 #endif
 }
 
@@ -106,7 +109,7 @@ cv_enter(kcondvar_t *cv, kmutex_t *mtx, lwp_t *l)
 {
 	sleepq_t *sq;
 
-	KASSERT(cv->cv_wmesg != NULL);
+	KASSERT(cv->cv_wmesg != deadcv && cv->cv_wmesg != NULL);
 	KASSERT((l->l_flag & LW_INTR) == 0);
 
 	l->l_cv_signalled = 0;
@@ -137,6 +140,8 @@ cv_exit(kcondvar_t *cv, kmutex_t *mtx, lwp_t *l, const int error)
 	if (__predict_false(error != 0) && l->l_cv_signalled != 0)
 		cv_signal(cv);
 
+	KASSERT(cv->cv_wmesg != deadcv && cv->cv_wmesg != NULL);
+
 	return error;
 }
 
@@ -151,13 +156,14 @@ cv_exit(kcondvar_t *cv, kmutex_t *mtx, lwp_t *l, const int error)
 static void
 cv_unsleep(lwp_t *l)
 {
-	uintptr_t addr;
+	kcondvar_t *cv;
 
 	KASSERT(l->l_wchan != NULL);
 	KASSERT(lwp_locked(l, l->l_sleepq->sq_mutex));
 
-	addr = (uintptr_t)l->l_wchan;
-	((kcondvar_t *)addr)->cv_waiters--;
+	cv = (kcondvar_t *)(uintptr_t)l->l_wchan;
+	KASSERT(cv->cv_wmesg != deadcv && cv->cv_wmesg != NULL);
+	cv->cv_waiters--;
 
 	sleepq_unsleep(l);
 }