std::stringstream has incomplete type and cannot be defined

Пытаюсь запихнуть форматированный вывод в output но при компилировании получаю ошибку - std::stringstream out has incomplete type and cannot be defined

void panel_flug::GetFlugInformation(int timestamp, double Latitude, double Longitude, float downlink_quality, double speed)
{
    std::stringstream output;
    output << "A: (0 min)\t"  << "m\n";
    output << "V: \t\t\t " << 2579 << "m\n";
    output << "G: \t\t\t " << 2579 << "m\n";
    output << "UAV Info\n";
    output << "S: " << roundToInt(speed / 3.6) << "km/h\n";
    output << "\nNächster WP : keiner" << std::endl;
    ui->pTE_Informationen->setPlainText(output.str().c_str());
}