diff --git a/lib/licenses.nix b/lib/licenses.nix
index 2262ae9ebbcf..e03ed38eb5eb 100644
--- a/lib/licenses.nix
+++ b/lib/licenses.nix
@@ -2,7 +2,7 @@
 let
 
   spdx = lic: lic // {
-    url = "http://spdx.org/licenses/${lic.spdxId}";
+    url = "http://spdx.org/licenses/${lic.spdxId}.html";
   };
 
 in
@@ -580,6 +580,11 @@ lib.mapAttrs (n: v: v // { shortName = n; }) rec {
     fullName = "Vovida Software License v1.0";
   };
 
+  watcom = spdx {
+    spdxId = "Watcom-1.0";
+    fullName = "Sybase Open Watcom Public License 1.0";
+  };
+
   w3c = spdx {
     spdxId = "W3C";
     fullName = "W3C Software Notice and License";
@@ -614,5 +619,4 @@ lib.mapAttrs (n: v: v // { shortName = n; }) rec {
     spdxId = "ZPL-2.1";
     fullName = "Zope Public License 2.1";
   };
-
 }
diff --git a/pkgs/development/compilers/jwasm/default.nix b/pkgs/development/compilers/jwasm/default.nix
new file mode 100644
index 000000000000..9800b33e7a9e
--- /dev/null
+++ b/pkgs/development/compilers/jwasm/default.nix
@@ -0,0 +1,27 @@
+{ stdenv, fetchFromGitHub
+, cmake }:
+
+with stdenv.lib;
+stdenv.mkDerivation rec {
+  name = "jwasm-${version}";
+  version = "git-2017-11-22";
+
+  src = fetchFromGitHub {
+    owner = "JWasm";
+    repo  = "JWasm";
+    rev    = "26f97c8b5c9d9341ec45538701116fa3649b7766";
+    sha256 = "0m972pc8vk8s9yv1pi85fsjgm6hj24gab7nalw2q04l0359nqi7w";
+  };
+
+  nativeBuildInputs = [ cmake ];
+
+  installPhase = "mkdir -p $out/bin ; cp jwasm $out/bin/";
+
+  meta = {
+    description = "A MASM-compatible x86 assembler";
+    homepage = http://jwasm.github.io/;
+    license = licenses.gpl2Plus;
+    maintainers = with maintainers; [ AndersonTorres ];
+    platforms = platforms.darwin ++ platforms.linux;
+  };
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 7e5a97490add..ee00bf2bdfb2 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -6366,6 +6366,8 @@ with pkgs;
 
   julia = julia_06;
 
+  jwasm =  callPackage ../development/compilers/jwasm { };
+
   kotlin = callPackage ../development/compilers/kotlin { };
 
   lazarus = callPackage ../development/compilers/fpc/lazarus.nix {