diff --git a/triggers/daml/BUILD.bazel b/triggers/daml/BUILD.bazel
index 59a8a24e28..3ec1d52ea9 100644
--- a/triggers/daml/BUILD.bazel
+++ b/triggers/daml/BUILD.bazel
@@ -22,6 +22,7 @@ version: 0.0.1
 dependencies:
   - daml-stdlib
   - daml-prim
+build-options: ["--ghc-option", "-Werror"]
 EOF
       $(location //compiler/damlc) build --project-root=$$TMP_DIR -o $$PWD/$(location daml-trigger.dar)
       rm -rf $$TMP_DIR
diff --git a/triggers/daml/Daml/Trigger.daml b/triggers/daml/Daml/Trigger.daml
index 038fffc18f..f2ac2dcee6 100644
--- a/triggers/daml/Daml/Trigger.daml
+++ b/triggers/daml/Daml/Trigger.daml
@@ -191,6 +191,10 @@ runTrigger userTrigger = LowLevel.Trigger
                 Some commandId -> (acs { pendingContracts = Map.delete commandId acs.pendingContracts }, Map.delete commandId state.commandsInFlight)
               state' = state { acs = acs', userState, commandsInFlight }
           in runRule userTrigger.rule time state'
+        MHeartbeat ->
+          let userState = userTrigger.updateState state.acs MHeartbeat state.userState
+              state' = state { userState }
+          in runRule userTrigger.rule time state'
 
 -- Internal API