diff --git a/src/main.rs b/src/main.rs
index 3a2786e..52ad0ef 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1067,8 +1067,7 @@ impl App {
             card(ui, p, "Sidetone", |ui| {
                 ui.label(RichText::new("Hear your own voice in the headset while you talk.").color(p.sub));
                 if let Some(v) = live_slider(ui, "sidetone", s.sidetone, 0..=128, |v| if v == 0 { "off".into() } else { format!("{}%", v * 100 / 128) }) {
-                    s.sidetone = v;
-                    let _ = self.w.headset.send(HeadsetCmd::Sidetone(v));
+                    let _ = self.w.headset.send(HeadsetCmd::Sidetone(v, std::mem::replace(&mut s.sidetone, v)));
                 }
             });
         }
@@ -1076,8 +1075,7 @@ impl App {
             card(ui, p, "Auto power-off", |ui| {
                 ui.label(RichText::new("Turn the headset off after this long without sound.").color(p.sub));
                 if let Some(v) = live_slider(ui, "idle", s.idle_minutes, 0..=90, |v| if v == 0 { "never".into() } else { format!("{v} min") }) {
-                    s.idle_minutes = v;
-                    let _ = self.w.headset.send(HeadsetCmd::Idle(v));
+                    let _ = self.w.headset.send(HeadsetCmd::Idle(v, std::mem::replace(&mut s.idle_minutes, v)));
                 }
             });
         }
diff --git a/src/workers.rs b/src/workers.rs
index e851430..35dc686 100644
--- a/src/workers.rs
+++ b/src/workers.rs
@@ -169,9 +169,10 @@ pub enum MouseCmd {
     Activate(zbus::OwnedObjectPath, &'static str),
 }
 
+/// (new, previous): the previous value goes back into settings if the headset rejects the new one.
 pub enum HeadsetCmd {
-    Sidetone(u32),
-    Idle(u32),
+    Sidetone(u32, u32),
+    Idle(u32, u32),
 }
 
 pub struct MicCmd {
@@ -404,14 +405,28 @@ fn headset(st: Shared, ctx: Context, rx: Receiver<HeadsetCmd>) {
         update(&st, &ctx, |s| s.headset = dev);
 
         match rx.recv_timeout(Duration::from_secs(30)) {
-            Ok(HeadsetCmd::Sidetone(v)) => report(&st, &ctx, audio::headset_set("-s", v), "Sidetone set"),
-            Ok(HeadsetCmd::Idle(v)) => report(&st, &ctx, audio::headset_set("-i", v), "Auto-off set"),
+            Ok(HeadsetCmd::Sidetone(v, prev)) => set_or_revert(&st, &ctx, "-s", v, prev, |s| &mut s.sidetone, "Sidetone set"),
+            Ok(HeadsetCmd::Idle(v, prev)) => set_or_revert(&st, &ctx, "-i", v, prev, |s| &mut s.idle_minutes, "Auto-off set"),
             Err(RecvTimeoutError::Timeout) => {}
             Err(RecvTimeoutError::Disconnected) => return,
         }
     }
 }
 
+/// The slider already saved `v`; put `prev` back if the headset didn't take it (unless it moved on since).
+fn set_or_revert(st: &Shared, ctx: &Context, flag: &str, v: u32, prev: u32, field: fn(&mut Settings) -> &mut u32, ok: &str) {
+    let r = audio::headset_set(flag, v);
+    if r.is_err() {
+        update(st, ctx, |s| {
+            let f = field(&mut s.settings);
+            if *f == v {
+                *f = prev;
+            }
+        });
+    }
+    report(st, ctx, r, ok);
+}
+
 // -------------------------------------------------------------------- mic
 
 fn mic(st: Shared, ctx: Context, rx: Receiver<MicCmd>) {