This: QCOMPARE(QLocale::c().toString(1234.0, 'f', 0), QString("1,234")); was the behavior until Qt 5.5 With Qt 5.6, this happens: Actual (QLocale::c().toString(1234.0, 'f', 0)): "1234" Expected (QString("1,234")) : "1,234" Is this an expected change? -- David Faure, faure at kde.org, http://www.davidfaure.fr Working on KDE Frameworks 5