Can't stop re-render for color background with useMemo React?

On each re-render it generates a new color. How do I cache the first color it gets initialized and re-use it each now?

  const backgroundColor = newBackgroundColor(); // some random color  const background = React.useMemo(() => {    return backgroundColor;  }, []);  const buttonStyle: React.CSSProperties = {          background: background,  };  return (<button style={buttonStyle}>  )