diff --git a/flake.nix b/flake.nix
index ceb7be9..143667f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -152,6 +152,14 @@
               # (systemd-boot's boot.json).
               nix.settings = {
                 max-jobs = 1;
+                # Hard ceiling on any local build's wall-clock time. Activation-
+                # time stitch derivations (boot.json, system-units, etc.) finish
+                # in well under a second; anything that doesn't return in 60s
+                # is by definition a heavy compile that has no business running
+                # on ATM hardware (kernel, electron, rustc). Kill it fast so
+                # the upgrade fails loudly instead of silently wedging the box
+                # for an hour. Time-bounds the max-jobs=1 escape hatch.
+                timeout = 60;
                 trusted-users = [ "root" "lamassu" ];
                 substituters = [ "https://cache.nixos.org" "https://aiolabs.cachix.org" ];
                 trusted-public-keys = [