diff --git a/README b/README
--- a/README
+++ b/README
@@ -10,8 +10,9 @@
 example) to jump directly to definition of any standard or foreign function
 he/she uses.
 
-Note, that haskdogs calls some Unix shell commands like 'test' or 'mkdir'
-so this tool will run, but probably fail to work on pure Windows platforms.
+Note, that haskdogs calls some Unix shell commands like 'test' or 'mkdir' via
+SHS so this tool will probably work on Linuxes and maybe Macs. Pure Windows
+will fail to run it.
 
 INSTALL
 =======
diff --git a/haskdogs.cabal b/haskdogs.cabal
--- a/haskdogs.cabal
+++ b/haskdogs.cabal
@@ -3,7 +3,7 @@
 -- http://www.haskell.org/cabal/release/cabal-latest/doc/users-guide/authors.html#pkg-descr.
 -- The name of the package.
 Name:                haskdogs
-Version:             0.1
+Version:             0.2
 Synopsis:            Generate ctags file for haskell project directory and it's deps
 Homepage:            http://github.com/ierton/haskdogs
 License:             BSD3
@@ -24,15 +24,15 @@
     example) to jump directly to definition of any standard or foreign function
     he/she uses.
 
-    Note, that haskdogs calls some Unix shell commands like 'test' or 'mkdir'
-    so this tool will likely fail to work on pure Windows platforms.
+    Note, that haskdogs calls some Unix shell commands like 'test' or 'mkdir' via
+    SHS so this tool will probably work on Linuxes and maybe Macs. Pure Windows
+    will fail to run it.
 
 Executable haskdogs
   Hs-source-dirs:       src
   Main-is:              haskdogs.hs
   Build-depends:        base >= 3 && < 5, Cabal >= 1.6, HSH >= 2.0.3, filepath >= 1.1.0.3
   Ghc-options:          -fwarn-tabs -Wall
-  Build-tools:          hasktags
   
 Source-repository head
   Type:     git
diff --git a/src/haskdogs.hs b/src/haskdogs.hs
--- a/src/haskdogs.hs
+++ b/src/haskdogs.hs
@@ -35,24 +35,51 @@
 inames2modules :: [String] -> IO [String]
 inames2modules is = forM is (iname2module) >>= return . nub . sort . filter (/=[])
 
+testdir dir fyes fno = do
+    ret <- run ("test",["-d", dir])
+    case ret of
+        ExitSuccess -> fyes
+        _ -> fno
+
 unpackModule p = do
-    srcdir <- glob "~" >>= return . (</> ".cabal/var/haskdogs/") . head
+    srcdir <- sourcedir
     let fullpath = srcdir </> p
-    ret <- run ("test",["-d", fullpath])
-    case ret of
-        ExitSuccess -> do
+    testdir fullpath 
+        (do 
             putStrLn $ "Already unpacked " ++ p
             return fullpath
-        _ -> do
+        ) 
+        (do 
             cd srcdir
             ec <- tryEC (runIO (cabal_unpack p))
             case ec of
                 Left _ -> return []
                 Right _ -> return fullpath
+        )
 
 unpackModules ms = mapM unpackModule ms >>= return . filter (/=[])
 
+which :: String -> IO (String, IO (String,ExitCode))
+which n = run ("which", [n])
+
+checkapp appname = do
+    (_,ec) <- which appname >>= return . snd >>= id
+    case ec of
+        ExitSuccess -> return ()
+        _ -> do
+            putStrLn $ "Please Install \"" ++ appname ++ "\" application"
+            exitWith ec
+
+-- Directory to unpack sources into
+sourcedir = glob "~" >>= return . (</> ".haskdogs") . head
+
+main :: IO ()
 main = do
+    checkapp "cabal"
+    checkapp "ghc-pkg"
+    checkapp "hasktags"
+    d <- sourcedir
+    testdir d (return ()) (run ("mkdir",["-p",d]))
     cwd <- run "pwd" >>= return . head
     ss_local <- findSources ["."]
     ss_l1deps <- findImports ss_local >>= inames2modules >>= unpackModules >>= findSources