Note that the error message says that an explicit package name is required...
One could go to the trouble of saying $main::thingy (even without 'use strict') to mean the thingy in the main symbol table. Sometimes this is real handy when you want to diddle package variables from outside the package. Some packages even document variables for you to use this way (Data::Dumper comes to mind).

On the other hand, most of the time, you probably wanted to use "my" anyway...

yours,
Michael