diff --git a/pkgs/applications/networking/mailreaders/thunderbird/default.nix b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
index 6d5dd577bf2..f2a088164d2 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird/default.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
@@ -13,7 +13,7 @@
   enableOfficialBranding ? false
 }:
 
-let version = "31.6.0"; in
+let version = "31.7.0"; in
 let verName = "${version}"; in
 
 stdenv.mkDerivation rec {
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "ftp://ftp.mozilla.org/pub/thunderbird/releases/${verName}/source/thunderbird-${verName}.source.tar.bz2";
-    sha1 = "147ba0f3c7da29a7814ee9ce4265fb107744559e";
+    sha1 = "90e18f8ecccdaf1ee39493223a7e3ad8b3b7bede";
   };
 
   buildInputs = # from firefox30Pkgs.xulrunner, but without gstreamer and libvpx
@@ -84,6 +84,8 @@ stdenv.mkDerivation rec {
     ../mozilla/mach configure
   '';
 
+  enableParallelBuilding = true;
+
   buildPhase =  "../mozilla/mach build";
 
   installPhase =