diff --git a/hosts/pi-server/upgrade-diff.nix b/hosts/pi-server/upgrade-diff.nix
new file mode 100644
index 0000000..1903966
--- /dev/null
+++ b/hosts/pi-server/upgrade-diff.nix
@@ -0,0 +1,8 @@
+{ pkgs, ... }: {
+  system.activationScripts.diff = {
+    supportsDryActivation = true;
+    text = ''
+      ${pkgs.nvd}/bin/nvd --nix-bin-dir=${pkgs.nix}/bin diff /run/current-system "$systemConfig"
+    '';
+  };
+}