Installing MongoDB Service with logs

Just tried to install MongoDB as a service on Windows 7, but came up with issues trying to specify where to store the logs...

http://www.mongodb.org/display/DOCS/Windows+Service

The example on the website shows a directory path, but when you look at the help in the command windows it says:

all output going to: c:mongodblogs logpath [c:mongodblogs] should be a file name not a directory

I'm not sure why, maybe the documentation isn't up to date, but specifying a physical file, like 'log.txt' the service installs fine.