diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
index 7441fce13a9..319e404e084 100644
--- a/sys/fs/nullfs/null_subr.c
+++ b/sys/fs/nullfs/null_subr.c
@@ -201,7 +201,7 @@ null_nodeget(mp, lowervp, vpp)
 	int error;
 
 	ASSERT_VOP_LOCKED(lowervp, "lowervp");
-	KASSERT(lowervp->v_usecount >= 1, ("Unreferenced vnode %p\n", vp));
+	KASSERT(lowervp->v_usecount >= 1, ("Unreferenced vnode %p\n", lowervp));
 
 	/* Lookup the hash firstly */
 	*vpp = null_hashget(mp, lowervp);