diff --git a/CabalHelper/Main.hs b/CabalHelper/Main.hs
--- a/CabalHelper/Main.hs
+++ b/CabalHelper/Main.hs
@@ -118,7 +118,7 @@
 main = do
   args <- getArgs
 
-  distdir:args' <- case args of
+  projdir:distdir:args' <- case args of
                     [] -> usage >> exitFailure
                     _ -> return args
 
@@ -159,6 +159,7 @@
   print =<< flip mapM cmds $$ \cmd -> do
   case cmd of
     "write-autogen-files":[] -> do
+      -- can't use @projdir@ here
       let pd = localPkgDescr lbi
        -- calls writeAutogenFiles
       initialBuildSteps distdir pd lbi v
diff --git a/CabalHelper/Wrapper.hs b/CabalHelper/Wrapper.hs
--- a/CabalHelper/Wrapper.hs
+++ b/CabalHelper/Wrapper.hs
@@ -46,6 +46,7 @@
 import CabalHelper.Data
 import CabalHelper.Common
 import CabalHelper.GuessGhc
+import CabalHelper.Sandbox (getSandboxPkgDb)
 
 usage :: IO ()
 usage = do
@@ -59,7 +60,7 @@
 \  [--with-ghc=GHC_PATH]\n\
 \  [--with-ghc-pkg=GHC_PKG_PATH]\n\
 \  [--with-cabal=CABAL_PATH]\n\
-\  DIST_DIR ( print-exe | [CABAL_HELPER_ARGS...] ) )\n"
+\  PROJ_DIR DIST_DIR ( print-exe | [CABAL_HELPER_ARGS...] ) )\n"
 
 data Options = Options {
           verbose       :: Bool
@@ -122,7 +123,7 @@
     "version":[] -> putStrLn $ showVersion version
     "print-appdatadir":[] -> putStrLn =<< appDataDir
     "print-build-platform":[] -> putStrLn $ display buildPlatform
-    distdir:args' -> do
+    projdir:distdir:args' -> do
       cfgf <- canonicalizePath (distdir </> "setup-config")
       mhdr <- getCabalConfigHeader cfgf
       case mhdr of
@@ -131,7 +132,7 @@
 \- Check first line of: %s\n\
 \- Maybe try: $ cabal configure" cfgf
         Just (hdrCabalVersion, _) -> do
-          eexe <- compileHelper opts hdrCabalVersion distdir
+          eexe <- compileHelper opts hdrCabalVersion projdir distdir
           case eexe of
               Left e -> exitWith e
               Right exe ->
@@ -140,21 +141,23 @@
                   _ -> do
                     (_,_,_,h) <- createProcess $ proc exe args
                     exitWith =<< waitForProcess h
+    _ -> error "invalid command line"
 
 appDataDir :: IO FilePath
 appDataDir = (</> "cabal-helper") <$> getAppUserDataDirectory "ghc-mod"
 
-compileHelper :: Options -> Version -> FilePath -> IO (Either ExitCode FilePath)
-compileHelper opts cabalVer distdir = withHelperSources $ \chdir -> do
+compileHelper :: Options -> Version -> FilePath -> FilePath -> IO (Either ExitCode FilePath)
+compileHelper opts cabalVer projdir distdir = withHelperSources $ \chdir -> do
   run [ compileCabalSource chdir -- TODO: here ghc's caching fails and it always
                                  -- recompiles, probably because we write the
                                  -- sources to a tempdir and they always look
                                  -- newer than the Cabal sources, not sure if we
                                  -- can fix this
       , Right <$> MaybeT (cachedExe cabalVer)
+      , compileSandbox chdir
       , compileGlobal chdir
       , cachedCabalPkg chdir
-      , MaybeT (Just <$> compileSandbox chdir)
+      , MaybeT (Just <$> compilePrivatePkgDb chdir)
       ]
 
  where
@@ -175,6 +178,15 @@
        vLog opts $ logMsg ++ "user/global package-db"
        liftIO $ compileWithPkg chdir Nothing ver
 
+   -- | Check if this version is available in the project sandbox
+   compileSandbox :: FilePath -> MaybeT IO (Either ExitCode FilePath)
+   compileSandbox chdir = do
+       sandbox <- MaybeT $ getSandboxPkgDb projdir (display buildPlatform) =<< ghcVersion opts
+       ver <- MaybeT $ find (== cabalVer) <$> listCabalVersions' opts (Just sandbox)
+       vLog opts $ logMsg ++ "sandbox package-db"
+       liftIO $ compileWithPkg chdir (Just sandbox) ver
+
+
    -- | Check if we already compiled this version of cabal into a private
    -- package-db
    cachedCabalPkg :: FilePath -> MaybeT IO (Either ExitCode FilePath)
@@ -190,8 +202,7 @@
    -- | See if we're in a cabal source tree
    compileCabalSource :: FilePath -> MaybeT IO (Either ExitCode FilePath)
    compileCabalSource chdir = do
-       let couldBeSrcDir = takeDirectory distdir
-           cabalFile = couldBeSrcDir </> "Cabal.cabal"
+       let cabalFile = projdir </> "Cabal.cabal"
            isCabalMagicVer = cabalVer == Version [1,9999] []
        cabalSrc <- liftIO $ doesFileExist cabalFile
 
@@ -206,11 +217,11 @@
          True -> liftIO $ do
            ver <- cabalFileVersion <$> readFile cabalFile
            vLog opts $ "compiling helper with local Cabal source tree"
-           compileWithCabalTree chdir ver couldBeSrcDir
+           compileWithCabalTree chdir ver projdir
 
    -- | Compile the requested cabal version into an isolated package-db
-   compileSandbox :: FilePath -> IO (Either ExitCode FilePath)
-   compileSandbox chdir = do
+   compilePrivatePkgDb :: FilePath -> IO (Either ExitCode FilePath)
+   compilePrivatePkgDb chdir = do
        db <- installCabal opts cabalVer `E.catch`
              \(SomeException _) -> errorInstallCabal cabalVer distdir
        compileWithPkg chdir (Just db) cabalVer
diff --git a/Distribution/Helper.hs b/Distribution/Helper.hs
--- a/Distribution/Helper.hs
+++ b/Distribution/Helper.hs
@@ -106,31 +106,35 @@
 -- as reading in Cabal's @LocalBuildInfo@ datatype from disk is very slow but
 -- running all possible queries against it at once is cheap.
 newtype Query m a = Query { unQuery :: StateT (Maybe SomeLocalBuildInfo)
-                                         (ReaderT (Programs, FilePath) m) a }
+                                         (ReaderT (Programs, FilePath, FilePath) m) a }
     deriving (Functor, Applicative, Monad, MonadIO)
 
 type MonadQuery m = ( MonadIO m
                     , MonadState (Maybe SomeLocalBuildInfo) m
-                    , MonadReader (Programs, FilePath) m)
+                    , MonadReader (Programs, FilePath, FilePath) m)
 
 run :: Monad m
-  => (Programs, FilePath) -> Maybe SomeLocalBuildInfo -> Query m a -> m a
+  => (Programs, FilePath, FilePath) -> Maybe SomeLocalBuildInfo -> Query m a -> m a
 run r s action = flip runReaderT r (flip evalStateT s (unQuery action))
 
 -- | @runQuery query distdir@. Run a 'Query'. @distdir@ is where Cabal's
 -- @setup-config@ file is located.
 runQuery :: Monad m
-         => FilePath -- ^ Path to @dist/@
+         => FilePath -- ^ Path to project directory, i.e. the one containing the
+                     -- @project.cabal@ file
+         -> FilePath -- ^ Path to @dist/@
          -> Query m a
          -> m a
-runQuery fp action = run (def, fp) Nothing action
+runQuery pd dd action = run (def, pd, dd) Nothing action
 
 runQuery' :: Monad m
          => Programs
+         -> FilePath -- ^ Path to project directory, i.e. the one containing the
+                     -- @project.cabal@ file
          -> FilePath -- ^ Path to @dist/@
          -> Query m a
          -> m a
-runQuery' progs fp action = run (progs, fp) Nothing action
+runQuery' progs pd dd action = run (progs, pd, dd) Nothing action
 
 getSlbi :: MonadQuery m => m SomeLocalBuildInfo
 getSlbi = do
@@ -196,7 +200,7 @@
     return ()
 
 getSomeConfigState :: MonadQuery m => m SomeLocalBuildInfo
-getSomeConfigState = ask >>= \(progs, distdir) -> do
+getSomeConfigState = ask >>= \(progs, projdir, distdir) -> do
   let progArgs = [ "--with-ghc="     ++ ghcProgram progs
                  , "--with-ghc-pkg=" ++ ghcPkgProgram progs
                  , "--with-cabal="   ++ cabalProgram progs
@@ -214,7 +218,7 @@
 
   res <- liftIO $ do
     exe  <- findLibexecExe "cabal-helper-wrapper"
-    out <- readProcess exe (distdir:args) ""
+    out <- readProcess exe (projdir:distdir:args) ""
     evaluate (read out) `E.catch` \(SomeException _) ->
       error $ concat ["getSomeConfigState", ": ", exe, " "
                      , intercalate " " (map show $ distdir:args)
@@ -239,7 +243,7 @@
                   -> m ()
 writeAutogenFiles distdir = liftIO $ do
   exe  <- findLibexecExe "cabal-helper-wrapper"
-  void $ readProcess exe [distdir, "write-autogen-files"] ""
+  void $ readProcess exe ["/nowhere/../..", distdir, "write-autogen-files"] ""
 
 -- | Get the path to the sandbox package-db in a project
 getSandboxPkgDb :: FilePath
diff --git a/cabal-helper.cabal b/cabal-helper.cabal
--- a/cabal-helper.cabal
+++ b/cabal-helper.cabal
@@ -1,10 +1,12 @@
 name:                cabal-helper
-version:             0.3.9.0
+version:             0.4.0.0
 synopsis:            Simple interface to some of Cabal's configuration state used by ghc-mod
 description:
-    @cabal-helper@ provides a library which wraps the internal use of executables
-    to lift the restrictions imposed by linking against versions of GHC before
-    @7.10@.
+    @cabal-helper@ provides a library which wraps the internal use of
+    anexecutable to lift the restrictions imposed by linking against versions of
+    GHC before @7.10@. This has the pleasant side effect of isolating the user
+    from having to deal with Cabal version changes manually as @cabal-helper@
+    can simply recompile it's helper program automatically as needed.
     .
     @cabal-helper@ uses a wrapper executable to compile the actual cabal-helper
     executable at runtime while linking against an arbitrary version of