diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c
index 04e66ccb3e53..f0bed3f9d4a2 100644
--- a/sys/kern/kern_lock.c
+++ b/sys/kern/kern_lock.c
@@ -517,14 +517,20 @@ transferlockers(from, to)
 
 	KASSERT(from != to, ("lock transfer to self"));
 	KASSERT((from->lk_flags&LK_WAITDRAIN) == 0, ("transfer draining lock"));
-	if (from->lk_waitcount == 0)
+
+	mtx_lock(from->lk_interlock);
+	if (from->lk_waitcount == 0) {
+		mtx_unlock(from->lk_interlock);
 		return;
+	}
 	from->lk_newlock = to;
 	wakeup((void *)from);
-	msleep(&from->lk_newlock, NULL, from->lk_prio, "lkxfer", 0);
+	msleep(&from->lk_newlock, from->lk_interlock, from->lk_prio,
+	    "lkxfer", 0);
 	from->lk_newlock = NULL;
 	from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE);
 	KASSERT(from->lk_waitcount == 0, ("active lock"));
+	mtx_unlock(from->lk_interlock);
 }