diff --git a/Haskell/Dupechecker.hs b/Haskell/Dupechecker.hs
index d3d8c52..ebe1b4f 100644
--- a/Haskell/Dupechecker.hs
+++ b/Haskell/Dupechecker.hs
@@ -1,6 +1,82 @@
+-- Duplicate file checker
+-- Finds duplicate files based on MD5
+--
+-- Author: rfw
+--
+-- This file has been placed in the public domain.
+
+import Control.Monad (foldM)
+import qualified Data.Hash.MD5 as MD5
+import Data.List (nub)
+import qualified Data.Map as Map
+import Data.Maybe (fromMaybe)
+import Data.String.Utils (join)
+import System (getArgs)
 import System.Directory (getDirectoryContents)
-import System.IO
+import System.FilePath (combine)
+import System.IO (withBinaryFile, hGetContents, IOMode(ReadMode))
+import System.IO.PlafCompat (getFileStatus, isDirectory)
+import Text.Printf (printf)
+
+type MD5HashMap = Map.Map Integer [FilePath]
+
+-- hash a single file and return the MD5 sum
+hashFile :: String -> IO Integer
+hashFile fileName = do
+    withBinaryFile fileName ReadMode $ \handle -> do
+        contents <- hGetContents handle
+        return $! MD5.md5i $ MD5.Str contents
+
+-- hash a directory and put them into an MD5 hash map
+hashDirectory :: MD5HashMap -> FilePath -> IO MD5HashMap
+hashDirectory hashes dirName = do
+    let banner = printf  "Scanning: %s" dirName
+    putStrLn banner
+    putStrLn $ [ '=' | _ <- [1..length banner] ]
+
+    contents <- getDirectoryContents dirName
+    statuses <- mapM getFileStatus contents
+
+    let files = map fst $ filter (not . isDirectory . snd) (zip contents statuses)
+
+    -- now hash the files and throw them into the map
+    foldM hashAndPut hashes files
+
+    where
+        hashAndPut hashes fileName = do
+            hash <- hashFile fileName
+            let fn = combine dirName fileName
+            existing <- maybe (return []) (notify hash fn) $ Map.lookup hash hashes
+            return $ Map.insert hash (fn:existing) hashes
+
+        notify hash fileName existing = do
+            putStrLn $ printf "%32x: %s, %s" hash fileName (head existing)
+            return existing
+
+-- hash multiple directories
+hashDirectories :: MD5HashMap -> [FilePath] -> IO MD5HashMap
+hashDirectories hashes dirs =
+    foldM hashDirectory hashes dirs
+
+-- generate a summary of duplicates
+generateSummary :: MD5HashMap -> IO ()
+generateSummary hashes = do
+    putStrLn ""
+    putStrLn "Summary"
+    putStrLn "======="
+    mapM_ summarize $ Map.toList hashes
+
+    where
+        summarize (_, [x]) = return ()
+        summarize (hash, fileNames) = do
+            putStrLn $ printf "%32x: %s" hash (join ", " fileNames)
 
-lisFiles = getDirectoryContents "/home/john/Pictures/Dupes"
+main :: IO ()
+main = do
+    argv <- getArgs
+    let dirs = nub argv
 
-main = print "Protype Stage"
+    if dirs == [] then
+        putStrLn "ERROR: At least one directory should be specified."
+    else
+        hashDirectories Map.empty dirs >>= generateSummary
diff --git a/Haskell/Makefile b/Haskell/Makefile
index e1e4fe8..787f08f 100644
--- a/Haskell/Makefile
+++ b/Haskell/Makefile
@@ -1,7 +1,5 @@
 all:    dupechecker
 
 dupechecker:
-	ghc -o Dupechecker-Haskell Dupechecker-Haskell.hs
-	chmod +x Dupechecker-Haskell
-	rm Dupechecker-Haskell.o
-	rm Dupechecker-Haskell.hi
+	ghc --make -o Dupechecker-Haskell Dupechecker.hs
+	rm Dupechecker.o Dupechecker.hi