Can't prevent close when overridding QDialog reject on Qt 5.0 / macOS

I have a QWizard-based dialog which guides the user through a firmware update. While the update is being installed, I want to prevent the dialog from being closed.

As suggested by the documentation, this can be accomplished by overrriding reject(). If the current page is the install page, reject is trapped, preventing the wizard from being closed.

void FirmwareUpdateWizard::reject()
{
if (currentId() == InstallPageId)

QWizard::reject();
}

The above code works fine on Windows using Qt 5.0. However, on macOS using Qt 5.0, the wizard window is always hidden after the reject call, regardless of whether or not it was trapped. It should be noted that when compiling against Qt 4.x, this bug does not exist and the window is not closed on macOS (as desired).