It should be noted that '~~', the Smartmatch Operator, is experimental: see "perl5180delta: The smartmatch family of features are now experimental".

I haven't investigated whether it makes a difference with this specific usage; however, it may be worth checking this (from "perlop: Smartmatch Operator"):

"First available in Perl 5.10.1 (the 5.10.0 version behaved differently), ..."