Funny Looking Blog Name During Registration Process

I'm testing my Multisite install, and I'm creating a test user, and I want the test user to create a new blog during registration process. On the registration page, where it says Blog URL (required), it looks like this:

http://__________________________.http://solofirm.net

(where the underlined part is where the test user would put the site name)

It would be a whole lot better if it looked like this:

http://_____________________.solofirm.net

How do I fix this?