diff --git a/xyz/openbmc_project/Sensor/Threshold/HardShutdown.interface.yaml b/xyz/openbmc_project/Sensor/Threshold/HardShutdown.interface.yaml
index bf6c4fd..4987414 100644
--- a/xyz/openbmc_project/Sensor/Threshold/HardShutdown.interface.yaml
+++ b/xyz/openbmc_project/Sensor/Threshold/HardShutdown.interface.yaml
@@ -45,3 +45,37 @@
 
           HardShutdownAlarmLow may be set to False to clear an alarm condition.
           The behavior of setting HardShutdownAlarmLow to True is undefined.
+
+signals:
+    - name: HardShutdownHighAlarmAsserted
+      description: >
+          The high threshold alarm asserted.
+      properties:
+         - name: SensorValue
+           type: double
+           description: >
+               The sensor value that triggered the alarm change.
+    - name: HardShutdownHighAlarmDeasserted
+      description: >
+          The high threshold alarm deasserted.
+      properties:
+         - name: SensorValue
+           type: double
+           description: >
+               The sensor value that triggered the alarm change.
+    - name: HardShutdownLowAlarmAsserted
+      description: >
+          The low threshold alarm asserted.
+      properties:
+         - name: SensorValue
+           type: double
+           description: >
+               The sensor value that triggered the alarm change.
+    - name: HardShutdownLowAlarmDeasserted
+      description: >
+          The low threshold alarm deasserted.
+      properties:
+         - name: SensorValue
+           type: double
+           description: >
+               The sensor value that triggered the alarm change.