Excel 2013 - Macros on Ribbon

I've added a custom tab to the ribbon (Excel 2013) and have a group called MyFunctions that calls some macros I wrote. The problem I've found is that if I delete/move the original Excel file that I wrote the custom functions in, Excel can't find them. Is this normal? I would have thought if you attach a macro to the Ribbon then it would store the code in the standard Excel template (start-up file) rather than looking at the spreadsheet I originally wrote the macro in.

In fact it OPENS the file with the macro in it, which is not what I want at all!

What do people do to get around this?

Cheers
-Rob