setWindowFilePath prints warning on Mac OS X

I use QWidget::setWindowFilePath and QWidget::setWindowIcon to setup the title bar of my application. I've noticed in recent versions of Qt when running my app within Qt creator I get the following warning printed out:

QWidget::setWindowFilePath: Error setting proxyicon for path (/Users/wstokes/Desktop/pUC19.dna):-5600

This is a little bizarre since my title bar looks great and I can cmd+click on the title bar icon to get a menu to browse the path to the current document (see attached screenshots). So this warning is just adding clutter to the application output since it gets printed every time i refresh the title bar with a new file path, e.g. every time I open a document in my app.