diff --git a/artiq-full/extras.nix b/artiq-full/extras.nix
index 3412543..88587f5 100644
--- a/artiq-full/extras.nix
+++ b/artiq-full/extras.nix
@@ -3,8 +3,8 @@ let
   condaBuild = import ./fast/conda/build.nix { inherit pkgs; };
   condaFakeSource = import ./fast/conda/fake-source.nix { inherit pkgs; };
   dualPackage = (
-    { name, version, src, pythonOptions ? {}, condaOptions ? {}, withManual ? true}:
-      {
+    { name, version, src, pythonOptions ? {}, condaOptions ? {}, enabled ? true, withManual ? true}:
+      pkgs.lib.optionalAttrs enabled ({
         "${name}" = pkgs.python3Packages.buildPythonPackage ({
           inherit version;
           name = "${name}-${version}";
@@ -38,7 +38,7 @@ let
               echo doc manual ${dest}/html index.html >> $out/nix-support/hydra-build-products
               '';
         };
-      })
+      }))
     );
   # https://github.com/m-labs/artiq/issues/23
   hidapi = pkgs.hidapi.overrideAttrs (oa: {
@@ -236,37 +236,25 @@ in
     };
     pythonOptions = {
       propagatedBuildInputs = [ pkgs.python3Packages.flake8 ];
-      checkInputs = [ pkgs.python3Packages.pytest pkgs.python3Packages.mypy pkgs.python3Packages.flake8 ];
-      checkPhase =
-        ''
-        pytest
-        mypy
-        flake8
-        '';
+      checkInputs = [ pkgs.python3Packages.pytestCheckHook ];
     };
     condaOptions = { dependencies = [ "flake8" ]; };
   }) // (dualPackage rec {
     name = "dax";
-    version = "6.3";
+    version = "6.4";
+    enabled = builtins.head (builtins.splitVersion version) == builtins.head (builtins.splitVersion artiq.version);
     withManual = false;
     src = pkgs.fetchgit {
       url = "https://gitlab.com/duke-artiq/dax.git";
       rev = "v${version}";
-      sha256 = "17bgqal8iyajnmp11wd59k4i8gpa3zf3cm7v8mjail5c8bnwyl4c";
+      sha256 = "08w0fpyyhk78i1qmych9kq3va02sm5k1z14yhzrfk9hhf5r7ypf8";
     };
     pythonOptions = {
       VERSIONEER_OVERRIDE = version;
       inherit (pkgs.python3Packages.pygit2) SSL_CERT_FILE;
       propagatedBuildInputs = [ artiq sipyco ]
         ++ (with pkgs.python3Packages; [ numpy scipy pyvcd natsort pygit2 matplotlib graphviz h5py networkx ]);
-      doCheck = false;
-      checkInputs = [ pkgs.python3Packages.pytest pkgs.python3Packages.mypy pkgs.python3Packages.flake8 ];
-      checkPhase =
-        ''
-        pytest
-        mypy
-        flake8
-        '';
+      checkInputs = [ pkgs.python3Packages.pytestCheckHook ];
     };
     condaOptions = { dependencies = [ "python>=3.7" "artiq" "sipyco" "numpy" "scipy" "pyvcd" "natsort" "pygit2" "matplotlib" "python-graphviz" "h5py" "networkx" ]; };
   }) // (dualPackage {
@@ -281,12 +269,7 @@ in
     pythonOptions = {
       propagatedBuildInputs = [ artiq pyqtgraph-qt5 ]
         ++ (with pkgs.python3Packages; [ numpy pyqt5 ]);
-      checkInputs = [ pkgs.python3Packages.mypy pkgs.python3Packages.flake8 ];
-      checkPhase =
-        ''
-        mypy
-        flake8
-        '';
+      doCheck = false;
     };
     condaOptions = { dependencies = [ "python>=3.5" "artiq" "numpy" "pyqt" "pyqtgraph" ]; };
   })