diff --git a/gf.cabal b/gf.cabal
index cec15550b..7922eb556 100644
--- a/gf.cabal
+++ b/gf.cabal
@@ -10,7 +10,7 @@ synopsis: Grammatical Framework
 description: GF, Grammatical Framework, is a programming language for multilingual grammar applications
 homepage: http://www.grammaticalframework.org/
 bug-reports: http://code.google.com/p/grammatical-framework/issues/list
-tested-with: GHC==7.4.2, GHC==7.6.2
+tested-with: GHC==7.4.2, GHC==7.6.3
 
 data-dir: src
 data-files: www/*.html
@@ -53,6 +53,10 @@ flag new-comp
   Description: Make -new-comp the default
   Default:     True
 
+flag custom-binary
+  Description: Use a customised version of the binary package
+  Default:     True
+
 library
   build-depends: base >= 4.2 && <5,
                  array,
@@ -63,6 +67,19 @@ library
                  pretty,
                  mtl
   hs-source-dirs: src/compiler src/runtime/haskell
+
+  if flag(custom-binary)
+    hs-source-dirs: src/binary
+    other-modules:
+      -- not really part of GF but I have changed the original binary library
+      -- and we have to keep the copy for now.
+      Data.Binary
+      Data.Binary.Put
+      Data.Binary.Get
+      Data.Binary.Builder
+  else
+    build-depends: binary
+
   extensions: 
   exposed-modules: 
     PGF
@@ -94,13 +111,6 @@ library
     GF.Data.ErrM
     GF.Data.Relation
     GF.Data.Operations
--- not really part of GF but I have changed the original binary library
--- and we have to keep the copy for now.
-    Data.Binary
-    Data.Binary.Put
-    Data.Binary.Get
-    Data.Binary.Builder
-    Data.Binary.IEEE754
 
 executable gf
   build-depends: base >= 4.2 && <5,
@@ -143,6 +153,13 @@ executable gf
   if impl(ghc>=7.0)
     ghc-options: -rtsopts
   hs-source-dirs: src/compiler src/runtime/haskell
+
+  if flag(custom-binary)
+    hs-source-dirs: src/binary
+    other-modules: Data.Binary.IEEE754
+  else
+    build-depends: binary, data-binary-ieee754
+
   extensions:
   main-is: GF.hs
   other-modules:
@@ -221,7 +238,6 @@ executable gf
     PGF.Binary
     PGF.Paraphrase
     PGF.TypeCheck
-    PGF.Binary
     PGF.Printer
     PGF.Optimize
     GFC
diff --git a/src/runtime/haskell/Data/Binary.hs b/src/binary/Data/Binary.hs
similarity index 100%
rename from src/runtime/haskell/Data/Binary.hs
rename to src/binary/Data/Binary.hs
diff --git a/src/runtime/haskell/Data/Binary/Builder.hs b/src/binary/Data/Binary/Builder.hs
similarity index 100%
rename from src/runtime/haskell/Data/Binary/Builder.hs
rename to src/binary/Data/Binary/Builder.hs
diff --git a/src/runtime/haskell/Data/Binary/Get.hs b/src/binary/Data/Binary/Get.hs
similarity index 100%
rename from src/runtime/haskell/Data/Binary/Get.hs
rename to src/binary/Data/Binary/Get.hs
diff --git a/src/runtime/haskell/Data/Binary/IEEE754.lhs b/src/binary/Data/Binary/IEEE754.lhs
similarity index 100%
rename from src/runtime/haskell/Data/Binary/IEEE754.lhs
rename to src/binary/Data/Binary/IEEE754.lhs
diff --git a/src/runtime/haskell/Data/Binary/Put.hs b/src/binary/Data/Binary/Put.hs
similarity index 100%
rename from src/runtime/haskell/Data/Binary/Put.hs
rename to src/binary/Data/Binary/Put.hs
diff --git a/src/compiler/GF/Grammar/Binary.hs b/src/compiler/GF/Grammar/Binary.hs
index 34cb153d2..ba12fde06 100644
--- a/src/compiler/GF/Grammar/Binary.hs
+++ b/src/compiler/GF/Grammar/Binary.hs
@@ -7,7 +7,7 @@
 --
 -----------------------------------------------------------------------------
 
-module GF.Grammar.Binary where
+module GF.Grammar.Binary(decodeModule,decodeModuleHeader,encodeModule) where
 
 import Prelude hiding (catch)
 import Control.Exception(catch,ErrorCall(..),throwIO)
@@ -28,7 +28,6 @@ import PGF.Binary
 -- Please change this every time when the GFO format is changed
 gfoVersion = "GF02"
 
-
 instance Binary Ident where
   put id = put (ident2bs id)
   get    = do bs <- get
@@ -295,13 +294,32 @@ instance Binary RawIdent where
   put = put . rawId2bs
   get = fmap rawIdentC get
 
-putGFOVersion = mapM_ (putWord8 . fromIntegral . ord) gfoVersion
-getGFOVersion = replicateM (length gfoVersion) (fmap (chr . fromIntegral) getWord8)
+--putGFOVersion = mapM_ (putWord8 . fromIntegral . ord) gfoVersion
+--getGFOVersion = replicateM (length gfoVersion) (fmap (chr . fromIntegral) getWord8)
+--putGFOVersion = put gfoVersion
+--getGFOVersion = get :: Get VersionMagic
+
+
+data VersionTagged a = Tagged {unV::a} | WrongVersion
+
+instance Binary a => Binary (VersionTagged a) where
+  put (Tagged a) = put (gfoBinVersion,a)
+  get = do ver <- get
+           if ver==gfoBinVersion
+             then fmap Tagged get
+             else return WrongVersion
+
+gfoBinVersion = (b1,b2,b3,b4)
+  where [b1,b2,b3,b4] = map (toEnum.fromEnum) gfoVersion :: [Word8]
+
 
 decodeModule :: FilePath -> IO SourceModule
-decodeModule fpath = decodeFile' fpath (getGFOVersion >> get)
-
-decodeModuleHeader fpath = decodeFile' fpath getVersionedMod
+decodeModule fpath = check =<< decodeFile' fpath
+  where
+    check (Tagged m) = return m
+    check _ = fail ".gfo file version mismatch"
+{-
+decodeModuleHeader fpath = decodeFile_ fpath getVersionedMod
   where
     getVersionedMod = do
       ver <- getGFOVersion
@@ -309,13 +327,19 @@ decodeModuleHeader fpath = decodeFile' fpath getVersionedMod
         then do (m,mtype,mstatus,mflags,mextend,mwith,mopens,med,msrc) <- get
                 return (Just (m,ModInfo mtype mstatus mflags mextend mwith mopens med msrc Nothing Map.empty))
         else return Nothing
-
+--}
+--{-
+decodeModuleHeader fpath = fmap check $ decodeFile' fpath
+  where
+    check (Tagged (m,mtype,mstatus,mflags,mextend,mwith,mopens,med,msrc)) =
+        (Just (m,ModInfo mtype mstatus mflags mextend mwith mopens med msrc Nothing Map.empty))
+    check _ = Nothing
+--}
 encodeModule :: FilePath -> SourceModule -> IO ()
-encodeModule fpath mo =
-  encodeFile_ fpath (putGFOVersion >> put mo)
+encodeModule fpath mo = encodeFile fpath (Tagged mo)
 
--- | like decodeFile_ but adds file name to error message if there was an error
-decodeFile' fpath get = addFPath fpath (decodeFile_ fpath get)
+-- | like 'decodeFile' but adds file name to error message if there was an error
+decodeFile' fpath = addFPath fpath (decodeFile fpath)
 
 -- | Adds file name to error message if there was an error,
 -- | but laziness can cause errors to slip through