diff --git a/Codec/Archive/Tar/Check.hs b/Codec/Archive/Tar/Check.hs
--- a/Codec/Archive/Tar/Check.hs
+++ b/Codec/Archive/Tar/Check.hs
@@ -112,7 +112,8 @@
 -- Given the expected subdirectory, this function checks all entries are within
 -- that subdirectroy.
 --
--- Note: This check must be used in conjunction with 'checkSecurity'.
+-- Note: This check must be used in conjunction with 'checkSecurity'
+-- (or 'checkPortability').
 --
 checkTarbomb :: FilePath -> Entries e -> Entries (Either e TarBombError)
 checkTarbomb expectedTopDir = checkEntries (checkEntryTarbomb expectedTopDir)
@@ -189,8 +190,9 @@
   | otherwise = Nothing
 
   where
-    posixPath   = fromTarPathToPosixPath   (entryTarPath entry)
-    windowsPath = fromTarPathToWindowsPath (entryTarPath entry)
+    tarPath     = entryTarPath entry
+    posixPath   = fromTarPathToPosixPath   tarPath
+    windowsPath = fromTarPathToWindowsPath tarPath
 
     portableFileType ftype = case ftype of
       NormalFile   {} -> True
@@ -201,7 +203,7 @@
 
     portableChar c = c <= '\127'
 
--- | Potential portability issues in a tar archive
+-- | Portability problems in a tar archive
 data PortabilityError
   = NonPortableFormat Format
   | NonPortableFileType
diff --git a/Codec/Archive/Tar/Read.hs b/Codec/Archive/Tar/Read.hs
--- a/Codec/Archive/Tar/Read.hs
+++ b/Codec/Archive/Tar/Read.hs
@@ -20,6 +20,8 @@
 import Numeric       (readOct)
 import Control.Exception (Exception)
 import Data.Typeable (Typeable)
+import Control.Applicative
+import Control.Monad
 
 import qualified Data.ByteString.Lazy as BS
 import qualified Data.ByteString.Lazy.Char8 as BS.Char8
@@ -194,11 +196,21 @@
 getString :: Int64 -> Int64 -> ByteString -> String
 getString off len = BS.Char8.unpack . BS.Char8.takeWhile (/='\0') . getBytes off len
 
+-- These days we'd just use Either, but in older versions of base there was no
+-- Monad instance for Either, it was in mtl with an anoying Error constraint.
+--
 data Partial e a = Error e | Ok a
 
 partial :: Partial e a -> Either e a
 partial (Error msg) = Left msg
 partial (Ok x)      = Right x
+
+instance Functor (Partial e) where
+    fmap = liftM
+
+instance Applicative (Partial e) where
+    pure  = return
+    (<*>) = ap
 
 instance Monad (Partial e) where
     return        = Ok
diff --git a/Codec/Archive/Tar/Types.hs b/Codec/Archive/Tar/Types.hs
--- a/Codec/Archive/Tar/Types.hs
+++ b/Codec/Archive/Tar/Types.hs
@@ -465,3 +465,7 @@
 instance Monoid (Entries e) where
   mempty      = Done
   mappend a b = foldEntries Next b Fail a
+
+instance Functor Entries where
+  fmap f = foldEntries Next Done (Fail . f)
+
diff --git a/tar.cabal b/tar.cabal
--- a/tar.cabal
+++ b/tar.cabal
@@ -1,12 +1,12 @@
 name:            tar
-version:         0.4.0.1
+version:         0.4.1.0
 license:         BSD3
 license-file:    LICENSE
 author:          Bjorn Bringert <bjorn@bringert.net>
                  Duncan Coutts <duncan@community.haskell.org>
 maintainer:      Duncan Coutts <duncan@community.haskell.org>
 copyright:       2007 Bjorn Bringert <bjorn@bringert.net>
-                 2008-2012 Duncan Coutts <duncan@community.haskell.org>
+                 2008-2015 Duncan Coutts <duncan@community.haskell.org>
 category:        Codec
 synopsis:        Reading, writing and manipulating ".tar" archive files.
 description:     This library is for working with \"@.tar@\" archive files. It
@@ -23,10 +23,15 @@
   type: darcs
   location: http://code.haskell.org/tar/
 
+flag old-time
+
 library
-  build-depends: base >= 3 && < 5, filepath,
-                 bytestring, directory,
-                 old-time, time
+  build-depends: base == 4.*, filepath,
+                 bytestring, directory
+  if flag(old-time)
+    build-depends: directory < 1.2, old-time
+  else
+    build-depends: directory >= 1.2, time
 
   exposed-modules:
     Codec.Archive.Tar