diff --git a/pkgs/namd.nix b/pkgs/namd.nix
index 0d54da9..5e23a1b 100644
--- a/pkgs/namd.nix
+++ b/pkgs/namd.nix
@@ -1,37 +1,54 @@
-{ stdenv, fetchurl
-, bash, tcsh }:
+{ stdenv, fetchgit, fetchFromGitHub
+, tcsh, tcl-8_5, fftwSinglePrec }:
 
 stdenv.mkDerivation rec {
   version = "2.11";
   name = "namd-${version}";
 
-  src = fetchurl {
-    url = "http://ppomorsk.sharcnet.ca/namd-${version}.tar.gz";
-    sha256 = "1ylrxy8iqmsr64z82nr9cf3vvq9hbdav128fs2czm46y999dpls1";
-  };
+  srcs = [
+    (fetchgit {
+      name = "namd-${version}-src";
+      url = "https://charm.cs.illinois.edu/gerrit/namd.git";
+      rev = "release-2-11";
+      sha256 = "0msxc1zwjsjb5iynm2hzyvk42wrkbaw234kjcmaxv4zvd3wb8qmw";
+    })
+    (fetchFromGitHub {
+      name = "charm-6.7.0-src";
+      owner = "UIUC-PPL";
+      repo = "charm";
+      rev = "v6.7.0";
+      sha256 = "0xcw0jnp8l7dkx3cq9qbyyvr8k5zbij7w1ings0xg6ryjmjgi92x";
+    })
+  ];
 
+  sourceRoot = "namd-${version}-src";
   postUnpack = ''
-    cd namd-${version}
-    tar -xf charm-*.tar
-    tar -xzf fftw-linux-x86_64.tar.gz
-    mv linux-x86_64 fftw
-    tar -xzf tcl*-linux-x86_64.tar.gz
-    mv tcl*-linux-x86_64 tcl
-    tar -xzf tcl*-linux-x86_64-threaded.tar.gz
-    mv tcl*-linux-x86_64-threaded tcl-threaded
-    cd ..
+    chmod -R u+w namd-${version}-src charm-*-src
+    mv charm-*-src namd-${version}-src/charm
   '';
+
+#  postUnpack = ''
+#    cd namd-${version}
+#    tar -xf charm-*.tar
+#    tar -xzf fftw-linux-x86_64.tar.gz
+#    mv linux-x86_64 fftw
+#    tar -xzf tcl*-linux-x86_64.tar.gz
+#    mv tcl*-linux-x86_64 tcl
+#    tar -xzf tcl*-linux-x86_64-threaded.tar.gz
+#    mv tcl*-linux-x86_64-threaded tcl-threaded
+#    cd ..
+#  '';
   patchPhase = ''
-    find charm-*/ -type f | xargs sed -i \
+    find charm -type f | xargs sed -i \
       -e 's,/bin/cp,cp,g' \
       -e 's,/bin/rm,rm,g' \
       -e 's,/lib/cpp,cpp,g'
   '';
   configurePhase = ''
-    tcsh -f ./config  Linux-x86_64-g++   --charm-arch multicore-linux64
+    tcsh -f ./config  Linux-x86_64-g++ --charm-arch multicore-linux64 --with-fftw3
   '';
   buildPhase = ''
-    cd charm-*/
+    cd charm
     ./build charm++ multicore-linux64 --no-build-shared --with-production
     cd ..
     cd Linux-x86_64-g++
@@ -49,7 +66,8 @@ stdenv.mkDerivation rec {
   '';
 
   buildInputs = [
-    bash
     tcsh
+    tcl-8_5
+    fftwSinglePrec
   ];
 }