diff --git a/urukul/default.nix b/urukul/default.nix
index 393033c..063b4f1 100644
--- a/urukul/default.nix
+++ b/urukul/default.nix
@@ -2,19 +2,32 @@
 let
   migen = (pkgs.callPackage ../artiq-fast/pkgs/python-deps.nix {}).migen;
   ise = import ./ise.nix { inherit pkgs; };
+  buildUrukulCpld = {version, src}: pkgs.stdenv.mkDerivation {
+    name = "urukul-cpld-${version}";
+    inherit src;
+    buildInputs = [(pkgs.python3.withPackages(ps: [migen]))] ++ (builtins.attrValues ise);
+    phases = ["buildPhase" "installPhase"];
+    buildPhase = "python $src/urukul_impl.py";
+    installPhase = 
+      ''
+      mkdir -p $out $out/nix-support
+      cp build/urukul.jed $out
+      echo file binary-dist $out/urukul.jed >> $out/nix-support/hydra-build-products
+      '';
+  };
 in
   {
-    urukul-cpld = pkgs.stdenv.mkDerivation {
-      name = "urukul-cpld";
+    urukul-cpld-master = buildUrukulCpld {
+      version = "master";
       src = <urukulSrc>;
-      buildInputs = [(pkgs.python3.withPackages(ps: [migen]))] ++ (builtins.attrValues ise);
-      phases = ["buildPhase" "installPhase"];
-      buildPhase = "python $src/urukul_impl.py";
-      installPhase = 
-        ''
-        mkdir -p $out $out/nix-support
-        cp build/urukul.jed $out
-        echo file binary-dist $out/urukul.jed >> $out/nix-support/hydra-build-products
-        '';
+    };
+    urukul-cpld-release = buildUrukulCpld rec {
+      version = "1.3.1";
+      src = pkgs.fetchFromGitHub {
+        owner = "quartiq";
+        repo = "urukul";
+        rev = "v${version}";
+        sha256 = "1nvarspqbf9f7b27j34jkkh4mj6rwrlmccmfpz5nnzk3h2j6zbqc";
+      };
     };
   }