I needed to use a named lexical there. Not really sure why that is.

Without seeing the other code, it's hard to say for sure, but it's possible that something else modifies $_ without localizing it appropriately.

As well as the function call format that you wrote it in.

Like I said, be very careful with your approach to calling import. I know what the documentation says about use, but I patched it before 5.16 so it was closer to reality. You're asking for trouble if you do it that way.