diff --git a/monitor/src/mmp.rs b/monitor/src/mmp.rs
index c9b4be5f..26c0c909 100644
--- a/monitor/src/mmp.rs
+++ b/monitor/src/mmp.rs
@@ -101,7 +101,7 @@ fn handle_connection(
         if cmd == "qmp_capabilities" {
             caps_done = true;
         }
-        if cmd == "quit" {
+        if cmd == "quit" || cmd == "system_powerdown" {
             return true;
         }
     }
@@ -130,6 +130,13 @@ pub fn dispatch(cmd: &str, svc: &Arc<Mutex<MonitorService>>) -> Value {
             s.quit();
             json!({"return": {}})
         }
+        "system_powerdown" => {
+            // QMP system_powerdown shuts down the VM. machina has no
+            // separate ACPI shutdown path, so reuse quit() which signals
+            // the run loop to stop -- semantically equivalent here.
+            s.quit();
+            json!({"return": {}})
+        }
         "query-cpus-fast" => {
             let cpus = s.query_cpus();
             let arr: Vec<Value> = cpus
diff --git a/tests/src/monitor.rs b/tests/src/monitor.rs
index 67f25058..8dfae9a1 100644
--- a/tests/src/monitor.rs
+++ b/tests/src/monitor.rs
@@ -137,6 +137,17 @@ fn test_mmp_quit() {
     assert!(svc.lock().unwrap().state.is_quit_requested());
 }
 
+#[test]
+fn test_mmp_system_powerdown() {
+    // QMP system_powerdown shuts down the VM. machina has no separate
+    // ACPI shutdown path, so dispatch must reuse quit() and return
+    // the empty success envelope.
+    let svc = make_svc();
+    let resp = mmp::dispatch("system_powerdown", &svc);
+    assert_eq!(resp["return"], serde_json::json!({}));
+    assert!(svc.lock().unwrap().state.is_quit_requested());
+}
+
 // ── HMP tests ───────────────────────────────────────
 
 #[test]