Issue #6104 has been updated by Luis Lavena. Disregard previous comment, the issue with Dir.glob is something different. <pre> irb(main):001:0> a = "foo" => "foo" irb(main):002:0> a.encoding => #<Encoding:Windows-1252> irb(main):003:0> File.join(a).encoding => #<Encoding:ASCII-8BIT> </pre> And more: <pre> irb(main):005:0> a = "a".encode(Encoding::UTF_8) => "a" irb(main):006:0> b = "b".encode(Encoding::UTF_8) => "b" irb(main):007:0> a.encoding => #<Encoding:UTF-8> irb(main):008:0> b.encoding => #<Encoding:UTF-8> irb(main):009:0> File.join(a, b).encoding => #<Encoding:ASCII-8BIT> </pre> ---------------------------------------- Bug #6104: File.join always returns as ASCII-8BIT regardless of input encoding https://bugs.ruby-lang.org/issues/6104 Author: Patrick Bennett Status: Open Priority: Normal Assignee: Usaku NAKAMURA Category: core Target version: 1.9.3 ruby -v: ruby 1.9.3p125 (2012-02-16) [i386-mingw32] I can show lots of different variations, but the simplest proof is: irb(main):001:0> File.join('foo'.encode('utf-8')).encoding => #<Encoding:ASCII-8BIT> -- http://bugs.ruby-lang.org/