Controller Subfolder Structure - Prevent Root Access

[eluser]haydenp[/eluser]
Hiya, possibly a silly question

I'm using a controller subfolder structure as follows:

controllers/admin/login.php

I have the default welcome.php controller sitting in the root of the controllers folder as follows:

controllers/welcome.php

I have the welcome.php controller set as my default_controller in the routes file.

The problem I have is ... if I access: http:/www.mywebsite.com/index.php/admin/ I get the welcome controller displaying the welcome page.

- Why is this ... I would have though a 404 would display as no controller is being specified?
- How can I prevent this and rather show a 404?

Many thanks