diff --git a/pkgs/development/compilers/ghc/head.nix b/pkgs/development/compilers/ghc/head.nix
index 66b939cdfed..cf0c569d3be 100644
--- a/pkgs/development/compilers/ghc/head.nix
+++ b/pkgs/development/compilers/ghc/head.nix
@@ -1,17 +1,19 @@
 { stdenv, fetchurl, ghc, perl, gmp, ncurses }:
 
 stdenv.mkDerivation rec {
-  version = "7.5.20120419";
+  version = "7.5.20120607";
 
   name = "ghc-${version}";
 
   src = fetchurl {
     url = "http://haskell.org/ghc/dist/current/dist/${name}-src.tar.bz2";
-    sha256 = "0fwq2s3syk3l4xx0m8x6h67snldlf3qk9bjjkvx46sgr0q3xjd05";
+    sha256 = "1xrdx646g5ip2f2jypbm46y6jis3ddf8bild2704swbl2j4yb3vb";
   };
 
   buildInputs = [ ghc perl gmp ncurses ];
 
+  enableParallelBuilding = true;
+
   buildMK = ''
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="${gmp}/lib"
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-includes="${gmp}/include"
diff --git a/pkgs/development/compilers/ghc/with-packages.nix b/pkgs/development/compilers/ghc/with-packages.nix
index 5f36db177ec..9313c54b908 100644
--- a/pkgs/development/compilers/ghc/with-packages.nix
+++ b/pkgs/development/compilers/ghc/with-packages.nix
@@ -10,6 +10,17 @@ stdenv.mkDerivation rec {
   unpackPhase = "true";
 
   installPhase = ''
+    numversion=$(${ghc}/bin/ghc --numeric-version)
+    majorversion=''${numversion%%.*}
+    minorversion=''${numversion#*.}
+    minorversion=''${minorversion%%.*}
+
+    if [[ $majorversion -gt 6 ]] && [[ $minorversion -gt 4 ]]; then
+      globalConf="--global-package-db"
+    else
+      globalConf="--global-conf"
+    fi
+
     originalTopDir="${ghc}/lib/ghc-${ghc.version}"
     originalPkgDir="$originalTopDir/package.conf.d"
     linkedTopDir="$out/lib"
@@ -57,7 +68,7 @@ stdenv.mkDerivation rec {
     done
 
     echo -n "Generating package cache "
-    ${ghc}/bin/ghc-pkg --global-conf $linkedPkgDir recache
+    ${ghc}/bin/ghc-pkg $globalConf $linkedPkgDir recache
     echo .
 
     echo -n "Generating wrappers "
@@ -73,7 +84,7 @@ stdenv.mkDerivation rec {
     done
 
     for prg in ghc-pkg ghc-pkg-${ghc.version}; do
-      makeWrapper ${ghc}/bin/$prg $out/bin/$prg --add-flags "--global-conf $linkedPkgDir"
+      makeWrapper ${ghc}/bin/$prg $out/bin/$prg --add-flags "$globalConf $linkedPkgDir"
       echo -n .
     done