diff --git a/Language/Haskell/GhcMod/CabalConfig.hs b/Language/Haskell/GhcMod/CabalConfig.hs
index 5612535..ed1fdeb 100644
--- a/Language/Haskell/GhcMod/CabalConfig.hs
+++ b/Language/Haskell/GhcMod/CabalConfig.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE CPP #-}
 
--- | Reading cabal @dist/setup-config@
+-- | This module facilitates extracting information from Cabal's on-disk
+-- 'LocalBuildInfo' (@dist/setup-config@).
 module Language.Haskell.GhcMod.CabalConfig (
     CabalConfig
   , cabalConfigDependencies
@@ -37,10 +38,12 @@ import Distribution.Simple.LocalBuildInfo (ComponentName)
 import System.FilePath ((</>))
 ----------------------------------------------------------------
 
+-- | 'Show'ed cabal 'LocalBuildInfo' string
 type CabalConfig = String
 
--- | Get file containing 'LocalBuildInfo' data. If it doesn't exist run @cabal
--- configure@ i.e. configure with default options like @cabal build@ would do.
+-- | Get contents of the file containing 'LocalBuildInfo' data. If it doesn't
+-- exist run @cabal configure@ i.e. configure with default options like @cabal
+-- build@ would do.
 getConfig :: Cradle -> IO CabalConfig
 getConfig cradle =
     readFile path `E.catch` (\(E.SomeException _) -> configure >> readFile path)
@@ -55,10 +58,12 @@ getConfig cradle =
 configPath :: FilePath
 configPath = localBuildInfoFile defaultDistPref
 
+-- | Get list of 'Package's needed by all components of the current package
 cabalConfigDependencies :: Cradle -> PackageIdentifier -> IO [Package]
 cabalConfigDependencies cradle thisPkg =
     configDependencies thisPkg <$> getConfig cradle
 
+-- | Extract list of depencenies for all components from 'CabalConfig'
 configDependencies :: PackageIdentifier -> CabalConfig -> [Package]
 configDependencies thisPkg config = map fromInstalledPackageId deps
  where
@@ -116,6 +121,8 @@ configDependencies thisPkg config = map fromInstalledPackageId deps
            Right x -> x
            Left msg -> error $ "reading config " ++ f ++ " failed ("++msg++")"
 
+-- | Find @field@ in 'CabalConfig'. Returns 'Left' containing a user readable
+-- error message with lots of context on failure.
 extractField :: CabalConfig -> String -> Either String String
 extractField config field =
     case extractParens <$> find (field `isPrefixOf`) (tails config) of
diff --git a/Language/Haskell/GhcMod/Monad.hs b/Language/Haskell/GhcMod/Monad.hs
index a23a411..36aabdd 100644
--- a/Language/Haskell/GhcMod/Monad.hs
+++ b/Language/Haskell/GhcMod/Monad.hs
@@ -49,7 +49,6 @@ import Language.Haskell.GhcMod.Types
 import Language.Haskell.GhcMod.Cradle
 import Language.Haskell.GhcMod.DynFlags
 import Language.Haskell.GhcMod.GhcPkg
-import Language.Haskell.GhcMod.GHCChoice
 import Language.Haskell.GhcMod.CabalApi
 import qualified Language.Haskell.GhcMod.Gap as Gap
 
@@ -200,7 +199,7 @@ initializeFlagsWithCradle :: GhcMonad m
         -> Cradle
         -> m ()
 initializeFlagsWithCradle opt c
-  | cabal     = withCabal |||> withSandbox
+  | cabal     = withCabal
   | otherwise = withSandbox
   where
     mCradleFile = cradleCabalFile c
diff --git a/test/MonadSpec.hs b/test/MonadSpec.hs
index 7594e88..74404f1 100644
--- a/test/MonadSpec.hs
+++ b/test/MonadSpec.hs
@@ -1,6 +1,9 @@
+{-# LANGUAGE ScopedTypeVariables #-}
 module MonadSpec where
 
 import Test.Hspec
+import Dir
+import Control.Applicative
 import Control.Monad.Error.Class
 import Language.Haskell.GhcMod.Types
 import Language.Haskell.GhcMod.Monad
@@ -17,3 +20,8 @@ spec = do
                          return "hello"
                      `catchError` (const $ fail "oh noes")
              a `shouldBe` (Left $ GMEString "oh noes")
+
+    describe "runGhcModT" $
+        it "complains if the cabal file fails to parse while a sandbox is present" $ withDirectory_ "test/data/broken-cabal" $ do
+          (a,_) <- runGhcModT defaultOptions (gmCradle <$> ask)
+          a `shouldSatisfy` (\(Left _) -> True)
diff --git a/test/data/broken-cabal/.cabal-sandbox/packages/00-index.cache b/test/data/broken-cabal/.cabal-sandbox/packages/00-index.cache
new file mode 100644
index 0000000..e69de29
diff --git a/test/data/broken-cabal/.cabal-sandbox/packages/00-index.tar b/test/data/broken-cabal/.cabal-sandbox/packages/00-index.tar
new file mode 100644
index 0000000..9df6499
Binary files /dev/null and b/test/data/broken-cabal/.cabal-sandbox/packages/00-index.tar differ
diff --git a/test/data/broken-cabal/cabal.sandbox.config.in b/test/data/broken-cabal/cabal.sandbox.config.in
new file mode 100644
index 0000000..43e48ce
--- /dev/null
+++ b/test/data/broken-cabal/cabal.sandbox.config.in
@@ -0,0 +1,25 @@
+-- This is a Cabal package environment file.
+-- THIS FILE IS AUTO-GENERATED. DO NOT EDIT DIRECTLY.
+-- Please create a 'cabal.config' file in the same directory
+-- if you want to change the default settings for this sandbox.
+
+
+local-repo: @CWD@/test/data/broken-cabal/.cabal-sandbox/packages
+logs-dir: @CWD@/test/data/broken-cabal/.cabal-sandbox/logs
+world-file: @CWD@/test/data/broken-cabal/.cabal-sandbox/world
+user-install: False
+package-db: @CWD@/test/data/broken-cabal/.cabal-sandbox/x86_64-linux-ghc-7.8.3-packages.conf.d
+build-summary: @CWD@/test/data/broken-cabal/.cabal-sandbox/logs/build.log
+
+install-dirs
+  prefix: @CWD@/test/data/broken-cabal/.cabal-sandbox
+  bindir: $prefix/bin
+  libdir: $prefix/lib
+  libsubdir: $arch-$os-$compiler/$pkgid
+  libexecdir: $prefix/libexec
+  datadir: $prefix/share
+  datasubdir: $arch-$os-$compiler/$pkgid
+  docdir: $datadir/doc/$arch-$os-$compiler/$pkgid
+  htmldir: $docdir/html
+  haddockdir: $htmldir
+  sysconfdir: $prefix/etc