diff --git a/ghc-pkg-lib.cabal b/ghc-pkg-lib.cabal
--- a/ghc-pkg-lib.cabal
+++ b/ghc-pkg-lib.cabal
@@ -1,6 +1,6 @@
 name:           ghc-pkg-lib
-version:        0.2.1
-cabal-version:  >=1.20
+version:        0.3
+cabal-version:  >=1.14
 build-type:     Simple
 author:         Thiago Arrais, JP Moresmau
 maintainer:     jp@moresmau.fr
@@ -13,6 +13,10 @@
 category:       Development
 homepage:       https://github.com/JPMoresmau/ghc-pkg-lib
 
+flag lib-Werror
+  default: False
+  manual: True
+
 library
   hs-source-dirs:   src
   build-depends:   
@@ -20,10 +24,14 @@
                     ghc-paths >=0.1.0,
                     filepath,
                     directory,
-                    Cabal >=1.18
+                    ghc,
+                    Cabal >=1.14
   ghc-options:      -Wall
   exposed-modules:  Language.Haskell.Packages
   default-language: Haskell98
+  
+  if flag(lib-Werror)
+    ghc-options: -Werror
 
 source-repository head
   type:     git
diff --git a/src/Language/Haskell/Packages.hs b/src/Language/Haskell/Packages.hs
--- a/src/Language/Haskell/Packages.hs
+++ b/src/Language/Haskell/Packages.hs
@@ -15,6 +15,7 @@
 
 import Prelude hiding (Maybe)
 import qualified System.Info
+import qualified Config
 import Control.Applicative
 import Data.List
 import Data.Maybe
@@ -71,7 +72,7 @@
     currentOS = System.Info.os
 
     ghcVersion :: String
-    ghcVersion = TOOL_VERSION_ghc
+    ghcVersion = Config.cProjectVersion
   in do
     -- Get the global package configuration database:
     global_conf <- do