This should be fixed by 2814f4b354: [perl #129350] anchored/floating substrings must be utf8 if target is If the target is utf8 and either the anchored or floating substrings are not, we need to create utf8 copies to check against. The state of the two substrings may not be the same, but we were only testing whichever we planned to check first. Hugo --- via perlbug: queue: perl5 status: pending release https://rt.perl.org/Ticket/Display.html?id=129350