diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -4,6 +4,11 @@
 
 ## Released changes
 
+### 0.4.0.1
+
+- fix too early abortion of process execution
+- show raw output on library parsing issues
+
 ### 0.4
 
 - provide required Java libraries in package data directory
diff --git a/call-alloy.cabal b/call-alloy.cabal
--- a/call-alloy.cabal
+++ b/call-alloy.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           call-alloy
-version:        0.4
+version:        0.4.0.1
 synopsis:       A simple library to call Alloy given a specification
 description:    Please see the README on GitHub at <https://github.com/marcellussiegburg/call-alloy#readme>
 category:       Language
@@ -61,6 +61,7 @@
     , mtl >=2.2 && <2.4
     , process ==1.6.*
     , split ==0.2.*
+    , transformers >=0.5.0.0 && <0.7
     , trifecta >=2 && <2.2
   default-language: Haskell2010
   if os(windows)
@@ -102,6 +103,7 @@
     , mtl >=2.2 && <2.4
     , process ==1.6.*
     , split ==0.2.*
+    , transformers >=0.5.0.0 && <0.7
     , trifecta >=2 && <2.2
   default-language: Haskell2010
   if os(windows)
diff --git a/src/Language/Alloy/Call.hs b/src/Language/Alloy/Call.hs
--- a/src/Language/Alloy/Call.hs
+++ b/src/Language/Alloy/Call.hs
@@ -27,6 +27,8 @@
 import Language.Alloy.Types             as Types
   (AlloyInstance, AlloySig, Entries, Object, Signature)
 
+import Control.Monad.Trans.Except       (runExceptT)
+
 {-|
 This function may be used to get all model instances for a given Alloy
 specification. It calls Alloy via a Java interface and parses the raw instance
@@ -55,8 +57,8 @@
   -- ^ The Alloy specification which should be loaded.
   -> IO [AlloyInstance]
 getInstancesWith config content =
-  map (either (error . show) id . parseInstance)
-  <$> getRawInstancesWith config content
+  getRawInstancesWith config content
+  >>= mapM (fmap (either (error . show) id) . runExceptT . parseInstance)
 
 {-|
 Check if there exists a model for the given specification. This function calls
diff --git a/src/Language/Alloy/Internal/Call.hs b/src/Language/Alloy/Internal/Call.hs
--- a/src/Language/Alloy/Internal/Call.hs
+++ b/src/Language/Alloy/Internal/Call.hs
@@ -147,11 +147,11 @@
         hPutStr hin content
         hFlush hin
         hClose hin
-        printContentOnError ph
   withTimeout hin hout herr ph (timeout config) $ do
     (out, err) <- fst <$> concurrently
       (concurrently (getOutput hout) (getOutput herr))
       evaluateAlloy
+    printContentOnError ph
     let err' = removeInfoLines err
     unless (null err') $ fail $ unpack $ BS.unlines err'
     return $ fmap (BS.intercalate "\n")
diff --git a/src/Language/Alloy/Parser.hs b/src/Language/Alloy/Parser.hs
--- a/src/Language/Alloy/Parser.hs
+++ b/src/Language/Alloy/Parser.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TupleSections #-}
 {-|
 Module      : Language.Alloy.Parser
@@ -16,12 +17,14 @@
   parseInstance,
   ) where
 
+import qualified Data.ByteString.Char8            as BS (putStrLn)
 import qualified Data.Set                         as S (fromList)
 import qualified Data.Map                         as M
   (alter, empty, insert, singleton)
 
 import Control.Applicative              ((<|>))
 import Control.Monad                    (void)
+import Control.Monad.IO.Class           (MonadIO (liftIO))
 import Control.Monad.Except             (MonadError, throwError)
 import Data.ByteString                  (ByteString)
 import Data.Functor                     (($>))
@@ -45,15 +48,21 @@
 Parse an Alloy instance from a given String.
 May fail with 'ErrInfo'.
 -}
-parseInstance :: (MonadError ErrInfo m) => ByteString -> m AlloyInstance
+parseInstance
+  :: (MonadIO m, MonadError ErrInfo m)
+  => ByteString
+  -> m AlloyInstance
 parseInstance inst = case parseByteString alloyInstance mempty inst of
-  Failure l -> throwError l
+  Failure l -> do
+    liftIO $ BS.putStrLn "Failed parsing Alloys response as AlloyInstance:"
+    liftIO $ BS.putStrLn inst
+    throwError l
   Success r -> return $ combineEntries r
 
 combineEntries :: [Entries (,)] -> AlloyInstance
-combineEntries = foldl createOrInsert M.empty
+combineEntries = foldr createOrInsert M.empty
   where
-    createOrInsert ys (s, e) = M.alter (Just . alterSig e) s ys
+    createOrInsert (s, e) ys = M.alter (Just . alterSig e) s ys
     alterSig e Nothing  = e { relation = uncurry M.singleton $ relation e}
     alterSig e (Just y) = y { relation = uncurry M.insert (relation e) (relation y) }