diff --git a/fktry/src/ui/fax.ts b/fktry/src/ui/fax.ts
index 6b286d0..85b9d34 100644
--- a/fktry/src/ui/fax.ts
+++ b/fktry/src/ui/fax.ts
@@ -64,7 +64,7 @@ export function createFax(data: GameData): Fax {
       void stampEl.offsetWidth; // force reflow so the animation re-runs
       cls(stampEl, 'is-on', true);
       clearTimeout(stampTimer);
-      stampTimer = setTimeout(() => cls(stampEl, 'is-on', false), STAMP_MS);
+      stampTimer = window.setTimeout(() => cls(stampEl, 'is-on', false), STAMP_MS);
     },
   };
 }