diff --git a/docs/superpowers/plans/2026-06-21-crucible-build-parity.md b/docs/superpowers/plans/2026-06-21-crucible-build-parity.md
index 1838d65..8020fdd 100644
--- a/docs/superpowers/plans/2026-06-21-crucible-build-parity.md
+++ b/docs/superpowers/plans/2026-06-21-crucible-build-parity.md
@@ -1439,7 +1439,7 @@ Edit `sow-assets-manifest/flake.nix`. Add the input:
 Change the outputs signature to `{ self, nixpkgs, sow-tools }`, delete the entire `crucibleVersion` / `crucibleArch` / `crucibleHashes` / `crucible = pkgs.stdenvNoCC.mkDerivation { ... }` block, and replace the `++ [ crucible ]` line in `packages` with:
 
 ```nix
-              ++ [ sow-tools.packages.${pkgs.system}.crucible ];
+              ++ [ sow-tools.packages.${pkgs.stdenv.hostPlatform.system}.crucible ];
 ```
 
 (`forAllSystems` here already passes `pkgs`; `pkgs.system` is available.)