Recent versions of Devel::PPPort on Windows with Visual Studio built `perl` fail tests in t\mess.t because $0 is interpolated into regex patterns without the use of quotemeta[1]. In this case, $0 contains `\` as directory separators. This is necessary, because nmake tries to interpret part of a filename as a command line argument if it contains `/` characters. An easy fix is to use \Q$0\E instead of plain $0 in patterns. Here's a test report: http://www.cpantesters.org/cpan/report/e484fd2f-6c51-1014-9811-fe131a8368d1 HTH, -- Sinan [1]: https://www.nu42.com/2014/11/youve-gotta-quotemeta.html