QTextLayout::maximumWidth() doesn't handle spaces correctly

#include <QGuiApplication>
#include <QTextLayout>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    const QString text("text                                text");

    QTextLayout referenceLayout(text);
    referenceLayout.beginLayout();
    while (referenceLayout.createLine().isValid()) { }
    referenceLayout.endLayout();

    QTextLayout layout(text);
    layout.beginLayout();
    for (auto line = layout.createLine(); line.isValid(); line = layout.createLine())
        line.setLineWidth(40);
    layout.endLayout();

    qreal refMaxWidth = referenceLayout.maximumWidth();
    qDebug() << "reference maxwidth:" << refMaxWidth;

    qreal wrappedMaxWidth = layout.maximumWidth();
    qDebug() << "wrapped maxwidth:" << wrappedMaxWidth;

    Q_ASSERT(qFuzzyCompare(refMaxWidth, wrappedMaxWidth));

    return 0;
}

reference maxwidth: 144.781
wrapped maxwidth: 79.7813
ASSERT: "qFuzzyCompare(refMaxWidth, wrappedMaxWidth)" in file ..\TextLayout\main.cpp, line 27