diff --git a/Backend.hs b/Backend.hs
index ab15974c8a..645bfdfc3f 100644
--- a/Backend.hs
+++ b/Backend.hs
@@ -33,7 +33,6 @@ module Backend (
 ) where
 
 import Control.Monad.State (liftIO, when)
-import Control.Monad (liftM)
 import System.IO.Error (try)
 import System.FilePath
 import System.Posix.Files
diff --git a/CryptoTypes.hs b/CryptoTypes.hs
index 944a9d34e0..ba22c4cbe8 100644
--- a/CryptoTypes.hs
+++ b/CryptoTypes.hs
@@ -9,11 +9,12 @@ module CryptoTypes where
 
 import Data.String.Utils
 
-data Cipher = Cipher String -- XXX ideally, this would be a locked memory region
+-- XXX ideally, this would be a locked memory region
+newtype Cipher = Cipher String
 
 data EncryptedCipher = EncryptedCipher String KeyIds
 
-data KeyIds = KeyIds [String]
+newtype KeyIds = KeyIds [String]
 
 instance Show KeyIds where
 	show (KeyIds ks) = join "," ks
diff --git a/Touch.hsc b/Touch.hsc
index fd3500f869..4f26855d21 100644
--- a/Touch.hsc
+++ b/Touch.hsc
@@ -16,7 +16,7 @@ module Touch (
 import Foreign
 import Foreign.C
 
-data TimeSpec = TimeSpec CTime
+newtype TimeSpec = TimeSpec CTime
 
 {- Changes the access and modification times of an existing file.
    Can follow symlinks, or not. Throws IO error on failure. -}