Found this interesting quote in N.T. Wright’s Romans commentary:
Paul’s whole thought is characterized by the free grace of God, and any suggestion that humans, whether Jewish or Gentile, might somehow put God in their debt, might perhaps earn their good standing within God’s people, would be anathema to him.
Of course, that is not all that N.T. Wright says about salvation, works, and assurance, but sure does not sound like works-righteousness to me.