diff --git a/src/main.ts b/src/main.ts
index 9146839..8755560 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -487,9 +487,12 @@ async function installAvailableUpdate() {
   let downloaded = 0
   let total = 0
 
+  const signedUpdate = availableUpdate
+  if (!signedUpdate) return
+
   try {
-    state.textContent = `Downloading FieldLens Print ${availableUpdate.version}…`
-    await availableUpdate.downloadAndInstall((event) => {
+    state.textContent = `Downloading FieldLens Print ${signedUpdate.version}…`
+    await signedUpdate.downloadAndInstall((event) => {
       if (event.event === 'Started') {
         total = event.data.contentLength ?? 0
         downloaded = 0