Memory leak when overwriting icons attached to widgets

I notice a memory leak whenever I overwrite icons that are attached to widgets in memory. Specifically, I'm talking about the 'QMainWindow' and 'QSystemTrayIcon' classes. I'm sure there are other cases; I just haven't looked for them.

Each time I give either one of those a new icon (at runtime), my memory footprint increases proportionately. Trying to suck the old icon out first and deleting it manually doesn't help. Are you able to implement some sort of automatic cleanup mechanism?