diff --git a/web/src/serviceWorker.ts b/web/src/serviceWorker.ts
index 5c26c91..e54d87c 100644
--- a/web/src/serviceWorker.ts
+++ b/web/src/serviceWorker.ts
@@ -10,6 +10,8 @@
 // To learn more about the benefits of this model and instructions on how to
 // opt-in, read https://bit.ly/CRA-PWA
 
+const VERSION = 1;
+
 const isLocalhost = Boolean(
   window.location.hostname === 'localhost' ||
     // [::1] is the IPv6 localhost address.