diff --git a/src/Main.hs b/src/Main.hs
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -8,9 +8,10 @@
 --------------------------------------------------------------------------------
 import           Control.Monad          (forM_)
 import           Data.List              (intercalate)
-import           Data.Maybe             (listToMaybe)
 import           Data.Version           (Version(..))
+import           Prelude                hiding (readFile)
 import           System.Console.CmdArgs
+import           System.IO.Strict       (readFile)
 
 
 --------------------------------------------------------------------------------
@@ -26,6 +27,7 @@
     { config   :: Maybe FilePath
     , verbose  :: Bool
     , defaults :: Bool
+    , inPlace  :: Bool
     , files    :: [FilePath]
     } deriving (Data, Show, Typeable)
 
@@ -36,6 +38,7 @@
     { config   = Nothing &= typFile &= help "Configuration file"
     , verbose  = False              &= help "Run in verbose mode"
     , defaults = False              &= help "Dump default config and exit"
+    , inPlace  = False              &= help "Overwrite the given files in place"
     , files    = []      &= typFile &= args
     } &= summary ("stylish-haskell-" ++ versionString version)
   where
@@ -58,8 +61,17 @@
         conf <- loadConfig verbose' (config sa)
         let steps = configSteps conf
         forM_ steps $ \s -> verbose' $ "Enabled " ++ stepName s ++ " step"
-        contents <- maybe getContents readFile filePath
-        putStr $ unlines $ runSteps filePath steps $ lines contents
+        mapM_ (file sa conf) files'
   where
     verbose' = makeVerbose (verbose sa)
-    filePath = listToMaybe $ files sa
+    files'   = if null (files sa) then [Nothing] else map Just (files sa)
+
+
+--------------------------------------------------------------------------------
+-- | Processes a single file, or stdin if no filepath is given
+file :: StylishArgs -> Config -> Maybe FilePath -> IO ()
+file sa conf mfp = do
+    contents <- maybe getContents readFile mfp
+    write $ unlines $ runSteps mfp (configSteps conf) $ lines contents
+  where
+    write = maybe putStr (if inPlace sa then writeFile else const putStr) mfp
diff --git a/src/StylishHaskell/Step/TrailingWhitespace.hs b/src/StylishHaskell/Step/TrailingWhitespace.hs
--- a/src/StylishHaskell/Step/TrailingWhitespace.hs
+++ b/src/StylishHaskell/Step/TrailingWhitespace.hs
@@ -5,7 +5,7 @@
 
 
 --------------------------------------------------------------------------------
-import           Data.Char            (isSpace)
+import           Data.Char           (isSpace)
 
 
 --------------------------------------------------------------------------------
diff --git a/src/StylishHaskell/Step/UnicodeSyntax.hs b/src/StylishHaskell/Step/UnicodeSyntax.hs
--- a/src/StylishHaskell/Step/UnicodeSyntax.hs
+++ b/src/StylishHaskell/Step/UnicodeSyntax.hs
@@ -1,16 +1,15 @@
 --------------------------------------------------------------------------------
-{-# LANGUAGE ViewPatterns #-}
 module StylishHaskell.Step.UnicodeSyntax
     ( step
     ) where
 
 
 --------------------------------------------------------------------------------
-import           Data.List                              (isPrefixOf, sort)
-import           Data.Map                               (Map)
-import qualified Data.Map                               as M
-import           Data.Maybe                             (maybeToList)
-import qualified Language.Haskell.Exts.Annotated        as H
+import           Data.List                           (isPrefixOf, sort)
+import           Data.Map                            (Map)
+import qualified Data.Map                            as M
+import           Data.Maybe                          (maybeToList)
+import qualified Language.Haskell.Exts.Annotated     as H
 
 
 --------------------------------------------------------------------------------
diff --git a/stylish-haskell.cabal b/stylish-haskell.cabal
--- a/stylish-haskell.cabal
+++ b/stylish-haskell.cabal
@@ -1,5 +1,5 @@
 Name:          stylish-haskell
-Version:       0.2.0.2
+Version:       0.3.0.0
 Synopsis:      Haskell code prettifier
 Homepage:      https://github.com/jaspervdj/stylish-haskell
 License:       BSD3
@@ -52,7 +52,8 @@
     filepath         >= 1.1  && < 1.4,
     haskell-src-exts >= 1.13 && < 1.14,
     syb              >= 0.3  && < 0.4,
-    yaml             >= 0.7  && < 0.8
+    yaml             >= 0.7  && < 0.8,
+    strict           >= 0.3  && < 0.4
 
 Test-suite stylish-haskell-tests
   Ghc-options:    -Wall
@@ -82,7 +83,8 @@
     filepath         >= 1.1  && < 1.4,
     haskell-src-exts >= 1.13 && < 1.14,
     syb              >= 0.3  && < 0.4,
-    yaml             >= 0.7  && < 0.8
+    yaml             >= 0.7  && < 0.8,
+    strict           >= 0.3  && < 0.4
 
 Source-repository head
   Type:     git
diff --git a/tests/StylishHaskell/Step/LanguagePragmas/Tests.hs b/tests/StylishHaskell/Step/LanguagePragmas/Tests.hs
--- a/tests/StylishHaskell/Step/LanguagePragmas/Tests.hs
+++ b/tests/StylishHaskell/Step/LanguagePragmas/Tests.hs
@@ -5,9 +5,9 @@
 
 
 --------------------------------------------------------------------------------
-import           Test.Framework                 (Test, testGroup)
-import           Test.Framework.Providers.HUnit (testCase)
-import           Test.HUnit                     ((@=?))
+import           Test.Framework                      (Test, testGroup)
+import           Test.Framework.Providers.HUnit      (testCase)
+import           Test.HUnit                          ((@=?))
 
 
 --------------------------------------------------------------------------------
diff --git a/tests/StylishHaskell/Step/TrailingWhitespace/Tests.hs b/tests/StylishHaskell/Step/TrailingWhitespace/Tests.hs
--- a/tests/StylishHaskell/Step/TrailingWhitespace/Tests.hs
+++ b/tests/StylishHaskell/Step/TrailingWhitespace/Tests.hs
@@ -5,9 +5,9 @@
 
 
 --------------------------------------------------------------------------------
-import           Test.Framework                 (Test, testGroup)
-import           Test.Framework.Providers.HUnit (testCase)
-import           Test.HUnit                     ((@=?))
+import           Test.Framework                         (Test, testGroup)
+import           Test.Framework.Providers.HUnit         (testCase)
+import           Test.HUnit                             ((@=?))
 
 
 --------------------------------------------------------------------------------
diff --git a/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs b/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs
--- a/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs
+++ b/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs
@@ -5,9 +5,9 @@
 
 
 --------------------------------------------------------------------------------
-import           Test.Framework                 (Test, testGroup)
-import           Test.Framework.Providers.HUnit (testCase)
-import           Test.HUnit                     ((@=?))
+import           Test.Framework                    (Test, testGroup)
+import           Test.Framework.Providers.HUnit    (testCase)
+import           Test.HUnit                        ((@=?))
 
 
 --------------------------------------------------------------------------------