diff --git a/src/service-worker.js b/src/service-worker.js
index fa352b39..e9be0988 100644
--- a/src/service-worker.js
+++ b/src/service-worker.js
@@ -6,7 +6,12 @@ const CACHE = `cache-${version}`;
 
 const ASSETS = [
     ...build, // the app itself
-    ...files // everything in `static`
+    // Exclude /fonts/ — 667 font files totalling ~134MB. Only 3 are used by the
+    // browser (app.css); the rest are badge-print fonts for server/Electron use.
+    // cache.addAll() is atomic, so including them would silently abort the entire
+    // SW install on most mobile devices (quota ~50-100MB). The browser's normal
+    // HTTP cache handles font requests when the print page is actually visited.
+    ...files.filter(f => !f.startsWith('/fonts/'))
 ];
 
 self.addEventListener('install', (event) => {