diff --git a/flake.nix b/flake.nix
index b68abd7..c2c6b2a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -113,7 +113,6 @@
     };
     binutils-arm = pkgs.callPackage binutils { platform = "arm"; target = "armv7-unknown-linux-gnueabihf"; };
 
-    # ======== default.nix
     # FSBL configuration supplied by Vivado 2020.1 for these boards:
     fsblTargets = ["zc702" "zc706" "zed"];
     sat_variants = [
@@ -129,14 +128,20 @@
       fwtype = if builtins.elem variant sat_variants then "satman" else "runtime";
 
       firmware = rustPlatform.buildRustPackage rec {
-        name = "firmware";
 
+        name = "firmware";
         src = ./src;
-        cargoLock = { lockFile = src/Cargo.lock; };
+        cargoLock = { 
+          lockFile = src/Cargo.lock;
+          outputHashes = {
+            "libasync-0.0.0" = "sha256-HUP9oRjm61+eh06igeG2Ziam0J3EQ1ZpYX5bAjyQGAM=";
+          };
+        };
 
         nativeBuildInputs = [
           pkgs.gnumake
           (pkgs.python3.withPackages(ps: (with artiqpkgs; [ ps.jsonschema migen migen-axi misoc artiq ])))
+          artiqpkgs.artiq
           zynqpkgs.cargo-xbuild
           pkgs.llvmPackages_9.llvm
           pkgs.llvmPackages_9.clang-unwrapped
@@ -163,6 +168,7 @@
         {
           nativeBuildInputs = [ 
             (pkgs.python3.withPackages(ps: (with artiqpkgs; [ ps.jsonschema migen migen-axi misoc artiq ])))
+            artiqpkgs.artiq
             artiqpkgs.vivado
           ];
         }
@@ -279,7 +285,7 @@
         artiqpkgs.artiq
         artiqpkgs.vivado
         binutils-arm
-        ];
+      ];
       XARGO_RUST_SRC = "${rustPlatform.rust.rustc}/lib/rustlib/src/rust/library";
       CLANG_EXTRA_INCLUDE_DIR = "${pkgs.llvmPackages_9.clang-unwrapped.lib}/lib/clang/9.0.1/include";
       OPENOCD_ZYNQ = "${zynq-rs}/openocd";