diff --git a/flake.nix b/flake.nix
index d9bb322..e2521d7 100644
--- a/flake.nix
+++ b/flake.nix
@@ -28,8 +28,8 @@
             # Embed the templates and static files at build time.
             ldflags = [ "-s" "-w" ];
 
-            # Remove stale vendor directory when dependencies change.
-            preBuild = "rm -rf vendor";
+            # Remove stale vendor directory before buildGoModule deletes it.
+            preConfigure = "find vendor -type f -exec chmod 666 {} \; 2>/dev/null || true; rm -rf vendor 2>/dev/null || find vendor -delete 2>/dev/null || true";
 
             nativeCheckInputs = with pkgs; [ ];