diff --git a/alpha.cabal b/alpha.cabal
--- a/alpha.cabal
+++ b/alpha.cabal
@@ -1,5 +1,5 @@
 name:           alpha
-version:        0.9.0.3
+version:        0.9.5
 synopsis:       A compiler for the Alpha language
 description:    Alpha is a programming language that aims at being very simple and 
                 low-level, so as to be efficient, while at the same time
@@ -20,8 +20,8 @@
   location: git://github.com/lih/Alpha.git
 
 executable alpha
-  build-depends:  base<=4.6.0.0, unix, containers, array, mtl, bytestring, bimap, ghc-prim, directory, filepath, cereal, parsec, transformers
+  build-depends:  base<=4.6.0.0, unix, containers, array, mtl, bytestring, bimap, ghc-prim, directory, filepath, cereal, parsec, transformers, bindings-posix
   main-is:        Alpha.hs
   other-modules:  Alpha, Compile, Compile.State, Compile.Utils, Context, Context.Language, Context.Types, Elf, ID, My.Control.Monad, My.Control.Monad.State, My.Control.Monad.TimeLine, My.Data.Graph, My.Data.List, My.Prelude, Options, PCode, PCode.Builtin, PCode.Instruction, PCode.Value, Serialize, Specialize, Specialize.Architecture, Specialize.Types, Specialize.X86, Syntax, Syntax.Parse, Translate
   hs-source-dirs: src
-  c-sources:      src/writeElf.c src/writeElf.h
+  c-sources:      src/writeElf.c
diff --git a/src/Alpha.hs b/src/Alpha.hs
--- a/src/Alpha.hs
+++ b/src/Alpha.hs
@@ -1,14 +1,16 @@
-{-# LANGUAGE ViewPatterns, NoMonomorphismRestriction #-}
+{-# LANGUAGE ViewPatterns, NoMonomorphismRestriction, ParallelListComp #-}
 import System.Environment as SE
 import System.FilePath
 import System.Directory
 import System.Posix.Files
+import Foreign hiding (void)
 import Data.Ord
 import Data.Maybe
 import qualified Data.Map as M
 import qualified Data.Bimap as BM
 import qualified Data.Serialize as Ser
 import qualified Data.ByteString as B
+import Data.ByteString.Unsafe
 import Data.List
 import My.Control.Monad
 import My.Control.Monad.State hiding ((<.>))
@@ -34,7 +36,7 @@
   PrintVersion -> printVersion
   Compile -> print s >> doCompile s
   
-version = "0.9.0.3"
+version = "0.9.5"
 printHelp = putStrLn helpMsg
 printVersion = putStrLn $ "Alpha version "++version
   
@@ -57,8 +59,11 @@
       importLanguage compileLanguage language
       rootSym <- stateF languageF $ internSym root
       getAddressComp (outputArch opts) rootSym
-      chunks <- sortBy (comparing fst) $< M.elems $< gets compAddresses
-      undefined
+      (addrs,ptrs) <- unzip $< sortBy (comparing fst) $< M.elems $< gets compAddresses
+      top <- gets compTop
+      contents <- B.concat $< sequence [withForeignPtr ptr $ \p -> unsafePackCStringLen (castPtr p,size) 
+                                       | ptr <- ptrs | size <- zipWith (-) (tail addrs++[top]) addrs]
+      writeElf language contents
     compileLanguage name = do
       source <- fromMaybe (fail $ "Couldn't find source file for language "++name) $< findSource name
       let langFile = languageFile name
@@ -75,7 +80,7 @@
       let sTree = concat $ parseAlpha src str
       code <- mapM compileExpr sTree
       languageState $ modify $ \e -> exportLanguage $ e { loadCode = foldr concatCode [] code }
-      where compileExpr expr = print expr >> do
+      where compileExpr expr = print (fmap Str expr) >> do
               symExpr <- languageState $ envCast expr
               trExpr <- doTransform symExpr
               (code,imports) <- languageState $ compile Nothing trExpr
diff --git a/src/Context.hs b/src/Context.hs
--- a/src/Context.hs
+++ b/src/Context.hs
@@ -7,7 +7,9 @@
               ,execCode) where
 
 import System.IO.Unsafe (unsafePerformIO)
+import Bindings.Posix.Sys.Mman
 import Foreign hiding (unsafePerformIO,unsafeForeignPtrToPtr)
+import Foreign.C
 import Foreign.ForeignPtr.Unsafe
 import Data.Maybe
 import Data.ByteString.Unsafe
@@ -25,6 +27,8 @@
 import Syntax
 import Specialize.Architecture
 
+foreign import ccall "mprotect" mprotect :: Ptr () -> CSize -> CInt -> IO CInt 
+
 withRef ref val x = readIORef ref >>= \v -> writeIORef ref val >> x >>= \x -> writeIORef ref v >> return x
 
 contextRef = unsafePerformIO $ newIORef (undefined :: Context)
@@ -77,7 +81,11 @@
 evalCode :: (FunPtr f -> f) -> Code -> IO f
 evalCode wrap code = do 
   binary <- snd $ specialize hostArch getAddressJIT code
-  unsafeUseAsCString binary $ return . wrap . castPtrToFunPtr
+  putStrLn $ "Evaluating code "++show code
+  unsafeUseAsCStringLen binary $ \(p,s) -> do 
+    mprotect (castPtr p) (fromIntegral s) (c'PROT_READ .|. c'PROT_WRITE .|. c'PROT_EXEC)
+    return $ wrap $ castPtrToFunPtr p
+execCode [] = return ()
 execCode instrs = do
   id <- languageState $ state createSym                
   join $ evalCode mkProc (Code [] instrs (symBind id))
diff --git a/src/Specialize.hs b/src/Specialize.hs
--- a/src/Specialize.hs
+++ b/src/Specialize.hs
@@ -8,4 +8,4 @@
 import Data.ByteString
 
 specialize :: Monad m => Architecture -> (ID -> m Int) -> Code -> (Int,m ByteString)
-specialize arch assoc (Code args code ret) = (1,return $ pack [0x83])
+specialize arch assoc (Code args code ret) = (1,return $ pack [0xC3])
diff --git a/src/writeElf.c b/src/writeElf.c
--- a/src/writeElf.c
+++ b/src/writeElf.c
@@ -1,8 +1,11 @@
 #include <unistd.h>
 #include <libelf.h>
-#include "writeElf.h"
 
 #define SETSTRUCT(v,t,vals...) { t tmp = vals; v = tmp; }
+
+typedef unsigned char byte;
+
+void writeElf(int fd,byte* data,int dataSize);
 
 void writeElf(int fd,byte* data,int dataSize) {
    Elf64_Ehdr eh;    Elf64_Phdr pht[1];
diff --git a/src/writeElf.h b/src/writeElf.h
deleted file mode 100644
--- a/src/writeElf.h
+++ /dev/null
@@ -1,20 +0,0 @@
-#ifndef WRITEELF
-#define WRITEELF
-
-typedef unsigned char byte;
-
-void writeElf(int fd,byte* data,int dataSize);
-
-#endif // WRITEELF
-
-/* 
-Copyright (c) 2012, Coiffier Marc <marc.coiffier@gmail.com>
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
-
-    Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
-    Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DPCodeECT, INDPCodeECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
-*/