diff --git a/flake.nix b/flake.nix
index d143495..fc8613b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -21,13 +21,16 @@
             version = "0.1.0";
             src = ./.;
 
-            vendorHash = "sha256-NbAa4QM/TI3BTuZs4glx9k3ZjSl2/2LQfKlQ7izR8Ho=";
+            vendorHash = ""; # auto-computed; update with actual hash after first build
             # Run: nix build .#packages.x86_64-linux.default
-            # It will fail with the correct hash. Replace it here.
+            # It will fail with the correct hash. Replace vendorHash with it.
 
             # Embed the templates and static files at build time.
             ldflags = [ "-s" "-w" ];
 
+            # Remove stale vendor directory when dependencies change.
+            preBuild = "rm -rf vendor";
+
             nativeCheckInputs = with pkgs; [ ];
 
             # Tests require network; they run in CI instead.