[Zope] squid and zope's inheritance

I really like the http cache manager that comes with zope, its a great idea. The only problem I have is that if you use zope's inheritance, you end up with stale pages in the cache. If I change file.html, it only gets purged as /file.html, and so when anyone accesses /subdir/file.html they still get a cached version. Is there any way to work around this besides not using inheritance? Thanks Adam