It seems self is null. Using the class name rather than the null instance worked around it. (I don't need this fix since I pass my own default page, but I found it while writing my code) Index: nevow/vhost.py =================================================================== --- nevow/vhost.py (revision 1131) +++ nevow/vhost.py (working copy) @@ -19,7 +19,7 @@ """ def getStyleSheet(self): - return self.stylesheet + return VirtualHostList.stylesheet def data_hostlist(self, context, data): return self.nvh.hosts.keys()