diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c
--- a/sys/kern/kern_mutex.c
+++ b/sys/kern/kern_mutex.c
@@ -284,8 +284,8 @@
 
 	KASSERT(kdb_active != 0 || SCHEDULER_STOPPED() ||
 	    !TD_IS_IDLETHREAD(curthread),
-	    ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
-	    curthread, m->lock_object.lo_name, file, line));
+	    ("mtx_lock() by idle thread %p on mutex %p @ %s:%d",
+	    curthread, m, file, line));
 	KASSERT(m->mtx_lock != MTX_DESTROYED,
 	    ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
 	KASSERT(LOCK_CLASS(&m->lock_object) != &lock_class_mtx_spin,
@@ -446,8 +446,8 @@
 		return (1);
 
 	KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td),
-	    ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
-	    curthread, m->lock_object.lo_name, file, line));
+	    ("mtx_trylock() by idle thread %p on mutex %p @ %s:%d",
+	    curthread, m, file, line));
 	KASSERT(m->mtx_lock != MTX_DESTROYED,
 	    ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
 	KASSERT(LOCK_CLASS(&m->lock_object) != &lock_class_mtx_spin,