diff --git a/Data/Time/Git.hs b/Data/Time/Git.hs
--- a/Data/Time/Git.hs
+++ b/Data/Time/Git.hs
@@ -1,14 +1,15 @@
 {-# LANGUAGE ForeignFunctionInterface #-}
 
-module Data.Time.Git (approxidate, io_approxidate, posixToUTC) where
+module Data.Time.Git (approxidate, approxidateIO) where
 
+import Data.Time (UTCTime)
+import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
 import Foreign hiding (unsafePerformIO)
-import Foreign.C.Types
 import Foreign.C.String
+import Foreign.C.Types
 import System.IO.Unsafe (unsafePerformIO)
-
-import Data.Time
-import Data.Time.Clock.POSIX
+import UnexceptionalIO (Unexceptional)
+import qualified UnexceptionalIO as UIO
 
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.UTF8 as BS (fromString)
@@ -21,22 +22,18 @@
 -- | Parse a date/time string and return Just a Unix timestamp.
 --   Return Nothing if the string could not be interpreted.
 --   If no timezone is in the string, the local timezone is used.
---   This is not in IO and you cannot safely ask it to parse strings like
---   \"now\" and \"yesterday\".
-approxidate :: String -> Maybe Integer
-approxidate = unsafePerformIO . io_approxidate
-
--- | Convert a Unix timestamp to a UTCTime
-posixToUTC :: Integer -> UTCTime
-posixToUTC = posixSecondsToUTCTime . realToFrac
+approxidate :: String -> Maybe UTCTime
+approxidate = unsafePerformIO . approxidateIO
 
 -- | Parse a date/time string and return Just a Unix timestamp.
 --   Return Nothing if the string could not be interpreted.
 --   If no timezone is in the string, the local timezone is used.
---   This is in IO so that you can safely ask it to parse strings like
+--   This is in IO so that you can ask it to parse strings like
 --   \"now\" and \"yesterday\".
-io_approxidate :: String -> IO (Maybe Integer)
-io_approxidate input =
+approxidateIO :: (Unexceptional m) => String -> m (Maybe UTCTime)
+approxidateIO input =
+	(fmap . fmap) (posixSecondsToUTCTime . realToFrac) $
+	UIO.unsafeFromIO $
 	BS.useAsCString (BS.fromString input) (\c_input ->
 		alloca (\c_error_ret -> do
 			poke c_error_ret 0
diff --git a/git-date.cabal b/git-date.cabal
--- a/git-date.cabal
+++ b/git-date.cabal
@@ -1,5 +1,5 @@
 name:            git-date
-version:         0.2.2
+version:         0.3.0
 cabal-version:   >= 1.8
 license:         GPL-2
 license-file:    COPYING
@@ -32,6 +32,7 @@
         build-depends:
                 base == 4.*,
                 bytestring,
+                unexceptionalio >= 0.3.0,
                 utf8-string,
                 time
 
diff --git a/tests/suite.hs b/tests/suite.hs
--- a/tests/suite.hs
+++ b/tests/suite.hs
@@ -4,7 +4,6 @@
 
 import Data.Int
 import Data.Time.Git
-import System.Locale
 import Data.Time
 import Data.Time.Clock.POSIX
 import System.IO.Unsafe
@@ -38,9 +37,8 @@
 
 prop_format :: DateFormat -> PositiveTime -> Bool
 prop_format (DateFormat fmt) (PositiveTime time) =
-	approxidate formatted == Just posix
+	approxidate formatted == Just (zonedTimeToUTC time)
 	where
-	posix = floor $ utcTimeToPOSIXSeconds $ zonedTimeToUTC time
 	formatted = formatTime defaultTimeLocale fmt time
 
 tests :: [Test]