diff --git a/artiq-fast/artiq-board-legacy.nix b/artiq-fast/artiq-board-legacy.nix
index 789d15a..ac591af 100644
--- a/artiq-fast/artiq-board-legacy.nix
+++ b/artiq-fast/artiq-board-legacy.nix
@@ -56,15 +56,15 @@ pkgs.python3Packages.toPythonModule (pkgs.stdenv.mkDerivation rec {
   version = import ./pkgs/artiq-version.nix (with pkgs; { inherit stdenv fetchgit git; });
   inherit src;
   phases = [ "buildPhase" "installCheckPhase" "installPhase" "checkPhase" ];
-  buildInputs = [
+  nativeBuildInputs = [
     vivado
     pkgs.gnumake
-    (pkgs.python3.withPackages(ps: with ps; [ jinja2 numpy artiqpkgs.migen artiqpkgs.microscope artiqpkgs.misoc artiqpkgs.jesd204b artiqpkgs.artiq ]))
     artiqpkgs.cargo
     artiqpkgs.rustc
     artiqpkgs.binutils-or1k
     artiqpkgs.llvm-or1k
   ];
+  buildInputs = [ (pkgs.python3.withPackages(ps: with ps; [ jinja2 numpy artiqpkgs.migen artiqpkgs.microscope artiqpkgs.misoc artiqpkgs.jesd204b artiqpkgs.artiq ])) ];
   buildPhase = 
     ''
     export CARGO_HOME=${cargoVendored}