diff --git a/pkgs/development/interpreters/spidermonkey/31.5.nix b/pkgs/development/interpreters/spidermonkey/31.5.nix
new file mode 100644
index 00000000000..4ee6658f59c
--- /dev/null
+++ b/pkgs/development/interpreters/spidermonkey/31.5.nix
@@ -0,0 +1,65 @@
+{ stdenv, fetchurl, pkgconfig, perl, python, zip, libffi, readline }:
+
+stdenv.mkDerivation rec {
+  version = "31.5.0";
+  name = "spidermonkey-${version}";
+
+  # the release notes point to some guys home directory, see
+  # https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Releases/31
+  # probably it would be more ideal to pull a particular tag/revision
+  # from the mercurial repo
+  src = fetchurl {
+    url = "https://people.mozilla.org/~sstangl/mozjs-31.5.0.tar.bz2";
+    sha256 = "1q8icql5hh1g3gzg5fp4rl9rfagyhm9gilfn3dgi7qn4i1mrfqsd";
+  };
+
+  buildInputs = [ pkgconfig perl python zip libffi readline ];
+
+  postUnpack = "sourceRoot=\${sourceRoot}/js/src";
+
+  preConfigure = ''
+    export LIBXUL_DIST=$out
+  '';
+
+  configureFlags = [
+    "--enable-threadsafe"
+    "--with-system-ffi"
+    "--enable-readline"
+
+    # there is at least one unfixed issue building the tests, so I didn't bother
+    "--disable-tests"
+
+    # enabling these because they're wanted by 0ad. They may or may
+    # not be good defaults for other uses.
+    "--enable-gcgenerational"
+    "--enable-shared-js"
+
+    # Due to a build-system bug, this means the exact opposite of what it says.
+    # It is required by gcgenerational.
+    "--disable-exact-rooting"
+  ];
+
+  # This addresses some build system bug. It's quite likely to be safe
+  # to re-enable parallel builds if the source revision changes.
+  enableParallelBuilding = false;
+
+  # see comment by --disable-tests
+  doCheck = false;
+
+  postFixup = ''
+    # The headers are symlinks to a directory that doesn't get put
+    # into $out, so they end up broken. Fix that by just resolving the
+    # symlinks.
+    for i in $(find $out -type l); do
+      cp --remove-destination "$(readlink "$i")" "$i";
+    done
+  '';
+
+  meta = with stdenv.lib; {
+    description = "Mozilla's JavaScript engine written in C/C++";
+    homepage = https://developer.mozilla.org/en/SpiderMonkey;
+    # TODO: MPL/GPL/LGPL tri-license.
+
+    maintainers = [ maintainers.goibhniu ];
+  };
+}
diff --git a/pkgs/games/0ad/data.nix b/pkgs/games/0ad/data.nix
index d3cc13307e7..ea9951e3339 100644
--- a/pkgs/games/0ad/data.nix
+++ b/pkgs/games/0ad/data.nix
@@ -5,7 +5,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "http://releases.wildfiregames.com/0ad-${version}-${releaseType}-unix-data.tar.xz";
-    sha256 = "6bf2234ef5043b14a3bbeda013fefed73ce2e564262f5e03b0801bfe671331d0";
+    sha256 = "0i5cf4n9qhzbi6hvw5lxapind24qpqfq6p5lrhx8gb25p670g95i";
   };
 
   patchPhase = ''
diff --git a/pkgs/games/0ad/default.nix b/pkgs/games/0ad/default.nix
index 5a0bdcd70a7..7ffa44c1fe4 100644
--- a/pkgs/games/0ad/default.nix
+++ b/pkgs/games/0ad/default.nix
@@ -1,5 +1,5 @@
 { stdenv, callPackage, fetchurl, python27
-, pkgconfig, spidermonkey_24, boost, icu, libxml2, libpng
+, pkgconfig, spidermonkey_31, boost, icu, libxml2, libpng
 , libjpeg, zlib, curl, libogg, libvorbis, enet, miniupnpc
 , openal, mesa, xproto, libX11, libXcursor, nspr, SDL
 , gloox, nvidia-texture-tools
@@ -9,7 +9,7 @@
 assert withEditor -> wxGTK != null;
 
 let
-  version = "0.0.17";
+  version = "0.0.18";
 
   releaseType = "alpha";
 
@@ -25,11 +25,11 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "http://releases.wildfiregames.com/0ad-${version}-${releaseType}-unix-build.tar.xz";
-    sha256 = "ef144d44fe8a8abd29a4642999a58a596b8f0d0e1f310065f5ce1dfbe29c3aeb";
+    sha256 = "15q3mv5k3lqzf0wrby2r93fs194ym13790i68q8azscs4v9h8bxx";
   };
 
   buildInputs = [
-    zeroadData python27 pkgconfig spidermonkey_24 boost icu
+    zeroadData python27 pkgconfig spidermonkey_31 boost icu
     libxml2 libpng libjpeg zlib curl libogg libvorbis enet
     miniupnpc openal mesa xproto libX11 libXcursor nspr
     SDL gloox nvidia-texture-tools
@@ -41,6 +41,10 @@ stdenv.mkDerivation rec {
     "-I${libXcursor}/include/X11"
   ];
 
+  patchPhase = ''
+    sed -i 's/MOZJS_MINOR_VERSION/false \&\& MOZJS_MINOR_VERSION/' source/scriptinterface/ScriptTypes.h
+  '';
+
   configurePhase = ''
     # Delete shipped libraries which we don't need.
     rm -rf libraries/source/{enet,miniupnpc,nvtt,spidermonkey}
@@ -58,7 +62,7 @@ stdenv.mkDerivation rec {
       --with-system-nvtt \
       --with-system-enet \
       --with-system-miniupnpc \
-      --with-system-mozjs24 \
+      --with-system-mozjs31 \
       ${ if withEditor then "--atlas" else "" } \
       --collada \
       --bindir="$out"/bin \
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index c097de4b5ec..689391ac18f 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5225,6 +5225,7 @@ let
   spidermonkey_185 = callPackage ../development/interpreters/spidermonkey/185-1.0.0.nix { };
   spidermonkey_17 = callPackage ../development/interpreters/spidermonkey/17.0.nix { };
   spidermonkey_24 = callPackage ../development/interpreters/spidermonkey/24.2.nix { };
+  spidermonkey_31 = callPackage ../development/interpreters/spidermonkey/31.5.nix { };
 
   supercollider = callPackage ../development/interpreters/supercollider {
     gcc = gcc48; # doesn't build with gcc49