diff --git a/PlatformString.hs b/PlatformString.hs
new file mode 100644
--- /dev/null
+++ b/PlatformString.hs
@@ -0,0 +1,46 @@
+{-# LANGUAGE CPP #-}
+{-
+Cross-platform, cross-GHC-version en/decoding of file paths, command-line arguments etc.
+
+Provides the PlatformString type alias, representing a possibly encoded
+string received from the OS environment or intended for it; and functions
+to convert these to and from regular non-encoded strings, which should
+work correctly on most platforms and GHC versions.
+
+-}
+
+module PlatformString (
+  PlatformString,
+  fromPlatformString,
+  toPlatformString
+)
+where
+
+#if __GLASGOW_HASKELL__ < 702
+import Codec.Binary.UTF8.String as UTF8 (decodeString, encodeString, isUTF8Encoded)
+import System.Info (os)
+#endif
+
+-- | A platform string is a string value received from or intended for the
+-- (current) operating system, such as a file path or command-line
+-- argument (or an environment variable's name or value ?).  On some
+-- platforms (unix) these are typically encoded, and on others (windows)
+-- they are not.  On unix we assume UTF-8 encoding, as recommended by
+-- http://www.dwheeler.com/essays/fixing-unix-linux-filenames.html)
+--
+type PlatformString = String
+
+fromPlatformString :: PlatformString -> String
+toPlatformString :: String -> PlatformString
+
+#if __GLASGOW_HASKELL__ < 702
+fromPlatformString s = if UTF8.isUTF8Encoded s then UTF8.decodeString s else s
+toPlatformString = case os of
+                     "unix" -> UTF8.encodeString
+                     "linux" -> UTF8.encodeString
+                     "darwin" -> UTF8.encodeString
+                     _ -> id
+#else
+fromPlatformString = id
+toPlatformString = id
+#endif
diff --git a/shelltestrunner.cabal b/shelltestrunner.cabal
--- a/shelltestrunner.cabal
+++ b/shelltestrunner.cabal
@@ -1,6 +1,6 @@
 name:           shelltestrunner
 -- sync with README.md, ANNOUNCE:
-version:        1.3
+version:        1.3.1
 category:       Testing
 synopsis:       A tool for testing command-line programs.
 description:
@@ -25,7 +25,7 @@
 
 executable shelltest
   main-is:        shelltest.hs
-  other modules:  PlatformString
+  other-modules:  PlatformString
   ghc-options:    -threaded -W -fwarn-tabs
   build-depends:
                  base                 >= 4     && < 5