} else if offsetEnd < 0 {
			return nil, fmt.Errorf("Last byte position is negative ('%d')", offsetEnd)
		}
	}

	switch {
	case offsetBegin > -1 && offsetEnd > -1:
		if offsetBegin > offsetEnd {
			return nil, errInvalidRange
		}
		return &HTTPRangeSpec{false, offsetBegin, offsetEnd}, nil
	case offsetBegin > -1:
		return &HTTPRangeSpec{false, offsetBegin, -1}, nil