diff --git a/flake.nix b/flake.nix
index 27ae3aa..5f31d8d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -35,13 +35,13 @@
 
 						rustZome = { crateCargoToml, holochain, workspacePath, excludedCrates ? [] }: 
 							let 
-							  system = holochain.devShells.holonix.system;
+							  system = holochain.legacyPackages.cowsay.system;
 							  pkgs = import inputs.nixpkgs {
 							    inherit system;
 							    overlays = [ (import inputs.rust-overlay) ];
 							  };
 
-							  rustToolchain = pkgs.rust-bin.nightly."2024-02-29".minimal.override {
+							  rustToolchain = pkgs.rust-bin.nightly.latest.minimal.override {
 							    # Set the build targets supported by the toolchain,
 							    # wasm32-unknown-unknown is required for trunk.
 							    targets = [ "wasm32-unknown-unknown" ];
diff --git a/nix/fixture/flake.lock b/nix/fixture/flake.lock
index 0c59e55..1e35fa2 100644
--- a/nix/fixture/flake.lock
+++ b/nix/fixture/flake.lock
@@ -540,7 +540,7 @@
       },
       "locked": {
         "lastModified": 0,
-        "narHash": "sha256-EC9uCt1eXennevMYMekgzJtqdxHpQTvnCOAWaewRUnM=",
+        "narHash": "sha256-FH1OUOHfGfcviSpQwf4/vLw4VqazLa4m+iGozfwzNRc=",
         "path": "../..",
         "type": "path"
       },