diff --git a/app/src/main/java/de/jeanlucmakiola/clockula/alarm/ring/UpcomingNotifications.kt b/app/src/main/java/de/jeanlucmakiola/clockula/alarm/ring/UpcomingNotifications.kt
index c4f182b..92e0c9b 100644
--- a/app/src/main/java/de/jeanlucmakiola/clockula/alarm/ring/UpcomingNotifications.kt
+++ b/app/src/main/java/de/jeanlucmakiola/clockula/alarm/ring/UpcomingNotifications.kt
@@ -6,6 +6,7 @@ import android.app.NotificationManager
 import android.app.PendingIntent
 import android.content.Context
 import android.content.Intent
+import android.os.Build
 import androidx.core.app.NotificationCompat
 import de.jeanlucmakiola.clockula.MainActivity
 import de.jeanlucmakiola.clockula.R
@@ -18,8 +19,9 @@ import de.jeanlucmakiola.clockula.domain.alarm.UpcomingNotice
  * (#16). Silent and low-importance: it is a way out for someone already awake,
  * not a second alarm. Its Dismiss is the engine's `dismissUpcomingOccurrence`
  * for the one occurrence it names, so it can never end a ring that has already
- * started; it asks for an unlock first, so a locked phone cannot be talked out
- * of its alarm by whoever picks it up.
+ * started; it asks for an unlock first (and below Android 12, where it cannot,
+ * the notice is kept off the secure lock screen), so a locked phone cannot be
+ * talked out of its alarm by whoever picks it up.
  */
 object UpcomingNotifications {
 
@@ -56,7 +58,15 @@ object UpcomingNotifications {
             .setContentText(text)
             .setCategory(NotificationCompat.CATEGORY_REMINDER)
             .setPriority(NotificationCompat.PRIORITY_LOW)
-            .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
+            // The Dismiss asks for an unlock from Android 12; below that the
+            // platform cannot, so there the notice stays off a locked screen.
+            .setVisibility(
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+                    NotificationCompat.VISIBILITY_PUBLIC
+                } else {
+                    NotificationCompat.VISIBILITY_SECRET
+                },
+            )
             .setOnlyAlertOnce(true)
             .setSilent(true)
             .setShowWhen(false)
diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index cfda3ee..c3bd2a0 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -1260,7 +1260,8 @@ the alarm's row for whoever opens the app instead.
   proves you are awake while an alarm sounds; before it, skipping is already one
   unchallenged switch away in the editor. The notification's Dismiss does ask
   for an **unlock** (`setAuthenticationRequired`), so a locked phone cannot be
-  talked out of its alarm by whoever picks it up.
+  talked out of its alarm by whoever picks it up. That flag needs Android 12;
+  below it the notice is `VISIBILITY_SECRET`, kept off the secure lock screen.
 - **Denied notifications** cost the notice and nothing else; the row's chip
   still works. A swipe is recorded as an `id@fireAt` key in a small
   SharedPreferences file through the notification's delete intent, which fires