Subdirectory install path problem

[davetest]

I've just uploaded a new 3.3.4 install to a sub directory, just like I always do, but in Settings I get:

PHP Code:

Website URL:
http://domain.com/subdomain/
Our suggestion is:   http://domain.com/subdomain// 


I cant work out why I'm getting the extra /
in .htaccess I'm getting RewriteBase /subdomain as expected/

Any thoughts