diff --git a/static/subscriptions.js b/static/subscriptions.js
index dd3bdd2..2b2c2b7 100644
--- a/static/subscriptions.js
+++ b/static/subscriptions.js
@@ -145,8 +145,16 @@ async function renderPushBar() {
       btn.disabled = true;
       const original = btn.textContent;
       try {
-        await pushClient.sendTest();
-        btn.textContent = "Sent ✓";
+        const r = await pushClient.sendTest();
+        if (!r.devices) {
+          btn.textContent = "No device";
+          alert("No device is registered for push on this account. Turn alerts off and on again on this device to re-subscribe.");
+        } else if (r.sent > 0) {
+          btn.textContent = "Sent ✓";
+        } else {
+          btn.textContent = "Failed";
+          alert("The push service rejected delivery to this device. Turn alerts off and on again to re-subscribe; if it keeps failing, the server's push (VAPID) keys may have changed.");
+        }
       } catch (err) {
         alert(err.message || "Couldn't send a test notification.");
       }