case f.Header.Length <= len64:
		bts[1] = 127
		binary.BigEndian.PutUint64(bts[2:10], uint64(f.Header.Length))
		n = 10

	default:
		return ws.ErrHeaderLengthUnexpected
	}

	if f.Header.Masked {
		bts[1] |= bit0
		n += copy(bts[n:], f.Header.Mask[:])
	}

	if _, err := w.Write(bts[:n]); err != nil {
		return err
	}

	_, err := w.Write(f.Payload)
	return err