doScript (UndoModes) breaks InDesign's Undo (CS4)

I wrote a little script. To make sure that I can undo it all in one go, I used:

app.doScript(main, undefined, undefined, UndoModes.fastEntireScript,"My script");

Once the script completes, InDesign's regular undo is broken. It no longer undoes separate steps, but will only revert to the point before which the script has been run.

What can I add at the end of the script to return things to normal?

Thanks,

Ariel