diff --git a/src/traffic_server/traffic_server.cc b/src/traffic_server/traffic_server.cc
index 3d6c630f919..65b2a758b79 100644
--- a/src/traffic_server/traffic_server.cc
+++ b/src/traffic_server/traffic_server.cc
@@ -2103,6 +2103,7 @@ task_threads_started_callback()
 {
   APIHook *hook = lifecycle_hooks->get(TS_LIFECYCLE_TASK_THREADS_READY_HOOK);
   while (hook) {
+    SCOPED_MUTEX_LOCK(lock, hook->m_cont->mutex, this_ethread());
     hook->invoke(TS_EVENT_LIFECYCLE_TASK_THREADS_READY, nullptr);
     hook = hook->next();
   }