diff --git a/src/ulib/system/thread_pool.cpp b/src/ulib/system/thread_pool.cpp
index 49a0864..d40d8a3 100644
--- a/src/ulib/system/thread_pool.cpp
+++ b/src/ulib/system/thread_pool.cpp
@@ -1,5 +1,4 @@
 #include "thread_pool.h"
-#include <fmt/format.h>
 
 namespace ulib {
 ThreadPool::ThreadPool(int max_thread_num,
diff --git a/src/ulib/system/thread_pool.h b/src/ulib/system/thread_pool.h
index 8431cc6..a5a03ee 100644
--- a/src/ulib/system/thread_pool.h
+++ b/src/ulib/system/thread_pool.h
@@ -2,6 +2,7 @@
 #define ULIB_SRC_ULIB_SYSTEM_THREAD_POOL_H_
 
 #include "thread.h"
+#include <fmt/format.h>
 #include "ulib/log/log.h"
 #include "ulib/concorrency/condition_variable.h"
 #include "ulib/concorrency/mutex.h"
@@ -39,7 +40,8 @@ public:
             tasks_.emplace([task]() { (*task)(); });
             if (tasks_.size() > idle_thread_num_
                 && workers_.size() < max_thread_num_) {
-                AddThread(thread_pool_name_ + std::to_string(workers_.size()));
+                AddThread(thread_pool_name_
+                          + fmt::format("{}", workers_.size()));
             }
             if (tasks_.size() > 1) {
                 tasks_cond_.NotifyAll();