Installing piwik in sub-sub-directory

I’ve installed and tested piwik on my host and it works well, but I wanted to use SSL instead of having passwords unencrypted.
My site has a shared ssl certificate such that https access to my site is at https://shared.net/mydomain.com/
So I wanted to install piwik at https://shared.net/mydomain.com/piwik/ i.e. a sub-directory of a sub-directory
The installation process lets me do that, but when I login, it is looking for pages/assets with urls of https://shared.net///piwik/
Anyway around this?