A method for imparting creep stabilization to a shaped article fabricated from an amorphous nitrile thermoplastic resin having a first glass transition temperature wherein the article is humidified to a moisture content of at least 1% and the glass transition temperature of the resin is lowered to a second glass transition temperature and the article while in a humidified state is heated to a temperature of 1* to 15*C below the second glass transition temperature for at least 0.5 hour.