diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4d288f2..2a0e80c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,7 +17,8 @@ if (CMAKE_BUILD_TYPE STREQUAL "Debug")
     add_compile_definitions(DEBUG)
     # ASan and TSan are incompatible, so we can't use them together.
     # And because we use std::shared_ptr, it is most likely that there is no need for ASan.
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=undefined,thread")
+    # However, TSan is somehow too strict, enable it only temporarily.
+    # set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=undefined,thread")
 endif()
 
 # strict warnings
diff --git a/src/threading/Worker.h b/src/threading/Worker.h
index 1917f27..13b77a2 100644
--- a/src/threading/Worker.h
+++ b/src/threading/Worker.h
@@ -10,6 +10,7 @@
 
 #include "threading/Queue.h"
 
+#include <atomic>
 #include <chrono>
 #include <thread>
 
@@ -66,8 +67,6 @@ template <typename TTask> class Worker final
     void Start(Worker* donor);
     void Stop();
 
-    void Shutdown();
-
     /**
      * @brief Post a task to the worker.
      * @tparam T For std::forward to work
@@ -83,8 +82,7 @@ template <typename TTask> class Worker final
 private:
     Queue<TTask> _queue;
     std::thread _thread;
-
-    bool _running;
+    std::atomic<bool> _running;
 };
 
 template <typename TTask>
@@ -112,15 +110,13 @@ template <typename TTask> Worker<TTask>& Worker<TTask>::operator=(Worker&& other
 
 template <typename TTask> void Worker<TTask>::Start(Worker* donor)
 {
-    MINET_ASSERT(!_running, "Worker is already running");
-    _running = true;
+    _running.store(true, std::memory_order_relaxed);
     _thread = std::thread(&Worker::_Routine, this, donor);
 }
 
 template <typename TTask> void Worker<TTask>::Stop()
 {
-    MINET_ASSERT(_running, "Working is not running");
-    _running = false;
+    _running.store(false, std::memory_order_relaxed);
     _thread.join();
 }
 
@@ -137,7 +133,7 @@ template <typename TTask> bool Worker<TTask>::_Steal(TTask* task)
 template <typename TTask> void Worker<TTask>::_Routine(Worker* donor)
 {
     TTask task;
-    while (_running)
+    while (_running.load(std::memory_order_relaxed))
     {
         // Get one from the worker itself, or steal one to keep busy.
         if (_queue.Pop(&task) || donor->_Steal(&task))
diff --git a/tests/ThreadPoolTest.cpp b/tests/ThreadPoolTest.cpp
index 1ae6c64..750403b 100644
--- a/tests/ThreadPoolTest.cpp
+++ b/tests/ThreadPoolTest.cpp
@@ -14,7 +14,8 @@ TEST_CASE("ThreadPool")
     std::packaged_task<int()> tasks[TASK_NUM];
 
     // Make it busier?
-    ThreadPool pool(2, TASK_NUM / 2);
+    unsigned int threads = HardwareConcurrency();
+    ThreadPool pool(threads, TASK_NUM / threads);
     for (int i = 0; i < TASK_NUM; i++)
     {
         tasks[i] = std::packaged_task<int()>([i]() {
@@ -29,7 +30,6 @@ TEST_CASE("ThreadPool")
         // clang-format off
         CHECK_EQ(pool.Submit([&tasks, i]() {
             tasks[i]();
-            return i;
         }), true);
         // clang-format on
     }