Perl 5.18 will introduce per process hash randomization and almost certainly will feature a new hash function. This means that code that has improper dependencies on perls hash order will become much more obvious.

Is your code ready?

Test your code on 5.17.6, and make sure it is ready for 5.18!

You might be pleasantly surprised: it might help you track down that nasty heisenbug you could never quite explain.