diff --git a/pkgs/development/compilers/ghc/head.nix b/pkgs/development/compilers/ghc/head.nix
index 330165437d5b..0d3301df60a3 100644
--- a/pkgs/development/compilers/ghc/head.nix
+++ b/pkgs/development/compilers/ghc/head.nix
@@ -1,13 +1,13 @@
 {stdenv, fetchurl, ghc, perl, gmp, ncurses, darwinInstallNameToolUtility}:
 
 stdenv.mkDerivation rec {
-  version = "7.3.20111212";
+  version = "7.4.0.20111219";
 
   name = "ghc-${version}";
 
   src = fetchurl {
-    url = "http://haskell.org/ghc/dist/current/dist/${name}-src.tar.bz2";
-    sha256 = "1i8zw3qaihzbgygdlip9d5g5321wv1yhashf8nrinwgy5649rsyf";
+    url = "http://haskell.org/ghc/dist/7.4.1-rc1/${name}-src.tar.bz2";
+    sha256 = "11imfag07wr9s5vf12yh6bz4hjfbw20i1c7n8py9fa4vx7va676n";
   };
 
   buildInputs = [ghc perl gmp ncurses] ++
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index f9243b7e05f3..0c9e92e7c9a7 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -2233,7 +2233,8 @@ let
   # Reasonably current HEAD snapshot. Should *always* be lowPrio.
   haskellPackages_ghcHEAD =
     haskellPackagesFun ../development/compilers/ghc/head.nix
-      (haskellPackages_ghc704.ghcWithPackages (self : [ self.alex self.happy ]))
+      # (haskellPackages_ghc704.ghcWithPackages (self : [ self.alex self.happy ]))
+      (if stdenv.isDarwin then ghc704Binary else ghc6121Binary)
       (x : x.ghcHEADPrefs) false false lowPrio;
 
   haxeDist = import ../development/compilers/haxe {