diff --git a/app.py b/app.py
index 32706fd..7911d7e 100644
--- a/app.py
+++ b/app.py
@@ -226,6 +226,10 @@ class Handler(BaseHTTPRequestHandler):
         if STATIC_DIR.resolve() not in target.parents or not target.is_file():
             target = STATIC_DIR / "index.html"
         body = target.read_bytes()
+        if target.name == "index.html":
+            # Versioned URLs, so no cache (a home-screen app's included) can serve an old client.
+            for asset in (b"/static/app.js", b"/static/styles.css"):
+                body = body.replace(asset + b'"', asset + b"?v=" + VERSION.encode() + b'"')
         self.send_response(HTTPStatus.OK)
         self.send_header("Content-Type", mimetypes.guess_type(target.name)[0] or "application/octet-stream")
         self.send_header("Content-Length", str(len(body)))