If Q_INVOKABLE method's return type is qint64 or quint64 its impossible to call it with QMetaObject::invokeMethod

call fails with no error message on the console:

// method signature
Q_INVOKABLE qint64 invokable2(const qint64 a);
// call
bool result2 = QMetaObject::invokeMethod(t, "invokable2", Qt::DirectConnection, Q_RETURN_ARG(qint64, returnVal2), Q_ARG(qint64, 777));

If return type is "long long int", or "int" all works fine.

This problem persists only with Qt 5.1.1/5.1.0.
Qt 4.8.4 has no such issue.

Excample application attached