diff --git a/Annex/Ssh.hs b/Annex/Ssh.hs
index a4cb5013eb..9fea51a929 100644
--- a/Annex/Ssh.hs
+++ b/Annex/Ssh.hs
@@ -43,6 +43,7 @@ import Annex.LockPool
 #endif
 
 import Control.Concurrent.STM
+import qualified Data.ByteString as S
 
 {- Some ssh commands are fed stdin on a pipe and so should be allowed to
  - consume it. But ssh commands that are not piped stdin should generally
@@ -325,7 +326,7 @@ sizeof_sockaddr_un_sun_path = 100
 {- Note that this looks at the true length of the path in bytes, as it will
  - appear on disk. -}
 valid_unix_socket_path :: FilePath -> Bool
-valid_unix_socket_path f = length (decodeW8 f) < sizeof_sockaddr_un_sun_path
+valid_unix_socket_path f = S.length (encodeBS f) < sizeof_sockaddr_un_sun_path
 
 {- Parses the SSH port, and returns the other OpenSSH options. If
  - several ports are found, the last one takes precedence. -}
diff --git a/Backend/Utilities.hs b/Backend/Utilities.hs
index bcb0c4bda4..0baaa476c9 100644
--- a/Backend/Utilities.hs
+++ b/Backend/Utilities.hs
@@ -11,6 +11,7 @@ import Annex.Common
 import Utility.Hash
 
 import qualified Data.ByteString as S
+import qualified Data.ByteString.Lazy as L
 
 {- Generates a keyName from an input string. Takes care of sanitizing it.
  - If it's not too long, the full string is used as the keyName.
@@ -21,11 +22,12 @@ genKeyName s
 	-- Avoid making keys longer than the length of a SHA256 checksum.
 	| bytelen > sha256len = encodeBS' $
 		truncateFilePath (sha256len - md5len - 1) s' ++ "-" ++ 
-			show (md5 (encodeBL s))
+			show (md5 bl)
 	| otherwise = encodeBS' s'
   where
 	s' = preSanitizeKeyName s
-	bytelen = length (decodeW8 s')
+	bl = encodeBL s
+	bytelen = fromIntegral $ L.length bl
 
 	sha256len = 64
 	md5len = 32
diff --git a/Utility/FileSystemEncoding.hs b/Utility/FileSystemEncoding.hs
index bb3738ed96..f9e98145a7 100644
--- a/Utility/FileSystemEncoding.hs
+++ b/Utility/FileSystemEncoding.hs
@@ -23,10 +23,6 @@ module Utility.FileSystemEncoding (
 	encodeBL',
 	decodeBS',
 	encodeBS',
-	decodeW8,
-	encodeW8,
-	encodeW8NUL,
-	decodeW8NUL,
 	truncateFilePath,
 	s2w8,
 	w82s,
@@ -148,16 +144,32 @@ encodeBS = S8.fromString
 {- Faster version that assumes the string does not contain NUL;
  - if it does it will be truncated before the NUL. -}
 decodeBS' :: S.ByteString -> FilePath
+#ifndef mingw32_HOST_OS
 decodeBS' = encodeW8 . S.unpack
+#else
+decodeBS' = S8.toString
+#endif
 
 encodeBS' :: FilePath -> S.ByteString
+#ifndef mingw32_HOST_OS
 encodeBS' = S.pack . decodeW8
+#else
+encodeBS' = S8.fromString
+#endif
 
 decodeBL' :: L.ByteString -> FilePath
+#ifndef mingw32_HOST_OS
 decodeBL' = encodeW8 . L.unpack
+#else
+decodeBL' = L8.toString
+#endif
 
 encodeBL' :: FilePath -> L.ByteString
+#ifndef mingw32_HOST_OS
 encodeBL' = L.pack . decodeW8
+#else
+encodeBL' = L8.fromString
+#endif
 
 {- Recent versions of the unix package have this alias; defined here
  - for backwards compatibility. -}
diff --git a/Utility/Metered.hs b/Utility/Metered.hs
index 53e253eccb..ec16e334c7 100644
--- a/Utility/Metered.hs
+++ b/Utility/Metered.hs
@@ -258,7 +258,7 @@ commandMeter' progressparser oh meterupdate cmd params =
 				unless (quietMode oh) $ do
 					S.hPut stdout b
 					hFlush stdout
-				let s = encodeW8 (S.unpack b)
+				let s = decodeBS b
 				let (mbytes, buf') = progressparser (buf++s)
 				case mbytes of
 					Nothing -> feedprogress prev buf' h