diff --git a/log.capnp b/log.capnp
index 0acceb4b627b09..699b5557084bb4 100644
--- a/log.capnp
+++ b/log.capnp
@@ -1278,6 +1278,7 @@ struct Sentinel {
     startOfRoute @3;
   }
   type @0 :SentinelType;
+  signal @1 :Int32;
 }
 
 struct ManagerState {