diff --git a/QMP/qmp-events.txt b/QMP/qmp-events.txt
index df190ac..2878058 100644
--- a/QMP/qmp-events.txt
+++ b/QMP/qmp-events.txt
@@ -252,6 +252,20 @@
 { "event": "SUSPEND",
      "timestamp": { "seconds": 1344456160, "microseconds": 309119 } }
 
+SUSPEND_DISK
+------------
+
+Emitted when the guest makes a request to enter S4 state.
+
+Data: None.
+
+Example:
+
+{ "event": "SUSPEND_DISK",
+     "timestamp": { "seconds": 1344456160, "microseconds": 309119 } }
+
+Note: QEMU shuts down when entering S4 state.
+
 VNC_CONNECTED
 -------------
 
diff --git a/hw/acpi.c b/hw/acpi.c
index effc7ec..f7950be 100644
--- a/hw/acpi.c
+++ b/hw/acpi.c
@@ -22,6 +22,7 @@
 #include "hw.h"
 #include "pc.h"
 #include "acpi.h"
+#include "monitor.h"
 
 struct acpi_table_header {
     uint16_t _length;         /* our length, not actual part of the hdr */
@@ -386,6 +387,7 @@
             break;
         default:
             if (sus_typ == s4) { /* S4 request */
+                monitor_protocol_event(QEVENT_SUSPEND_DISK, NULL);
                 qemu_system_shutdown_request();
             }
             break;
diff --git a/monitor.c b/monitor.c
index 3694590..586abae 100644
--- a/monitor.c
+++ b/monitor.c
@@ -432,6 +432,7 @@
     [QEVENT_BLOCK_JOB_CANCELLED] = "BLOCK_JOB_CANCELLED",
     [QEVENT_DEVICE_TRAY_MOVED] = "DEVICE_TRAY_MOVED",
     [QEVENT_SUSPEND] = "SUSPEND",
+    [QEVENT_SUSPEND_DISK] = "SUSPEND_DISK",
     [QEVENT_WAKEUP] = "WAKEUP",
     [QEVENT_BALLOON_CHANGE] = "BALLOON_CHANGE",
 };
diff --git a/monitor.h b/monitor.h
index 5f4de1b..4ef9a04 100644
--- a/monitor.h
+++ b/monitor.h
@@ -40,6 +40,7 @@
     QEVENT_BLOCK_JOB_CANCELLED,
     QEVENT_DEVICE_TRAY_MOVED,
     QEVENT_SUSPEND,
+    QEVENT_SUSPEND_DISK,
     QEVENT_WAKEUP,
     QEVENT_BALLOON_CHANGE,