diff --git a/include/ylt/coro_io/client_pool.hpp b/include/ylt/coro_io/client_pool.hpp
index e7387e213c..2d1a73d1ca 100644
--- a/include/ylt/coro_io/client_pool.hpp
+++ b/include/ylt/coro_io/client_pool.hpp
@@ -123,7 +123,7 @@ class client_pool : public std::enable_shared_from_this<
   async_simple::coro::Lazy<void> reconnect(std::unique_ptr<client_t>& client) {
     auto pre_time_point = std::chrono::steady_clock::now();
     bool ok = client_t::is_ok(co_await client->reconnect(host_name_));
-    for (int i = 0; !ok && i < pool_config_.connect_retry_count; ++i) {
+    for (unsigned int i = 0; !ok && i < pool_config_.connect_retry_count; ++i) {
       auto post_time_point = std::chrono::steady_clock::now();
       auto wait_time =
           pool_config_.reconnect_wait_time - (post_time_point - pre_time_point);
@@ -206,11 +206,12 @@ class client_pool : public std::enable_shared_from_this<
       if (clients.collecter_cnt_.compare_exchange_strong(expected, 1)) {
         collect_idle_timeout_client(
             this->shared_from_this(), clients,
-            std::max((is_short_client
-                          ? (std::min)(pool_config_.idle_timeout,
-                                       pool_config_.short_connect_idle_timeout)
-                          : pool_config_.idle_timeout),
-                     std::chrono::milliseconds{50}),
+            (std::max)(
+                (is_short_client
+                     ? (std::min)(pool_config_.idle_timeout,
+                                  pool_config_.short_connect_idle_timeout)
+                     : pool_config_.idle_timeout),
+                std::chrono::milliseconds{50}),
             pool_config_.idle_queue_per_max_clear_count)
             .via(coro_io::get_global_executor())
             .start([](auto&&) {
@@ -283,8 +284,7 @@ class client_pool : public std::enable_shared_from_this<
       : host_name_(host_name),
         pool_config_(pool_config),
         io_context_pool_(io_context_pool),
-        free_clients_(pool_config.max_connection) {
-  };
+        free_clients_(pool_config.max_connection){};
 
   client_pool(private_construct_token t, client_pools_t* pools_manager_,
               std::string_view host_name, const pool_config& pool_config,
@@ -293,8 +293,7 @@ class client_pool : public std::enable_shared_from_this<
         host_name_(host_name),
         pool_config_(pool_config),
         io_context_pool_(io_context_pool),
-        free_clients_(pool_config.max_connection) {
-  };
+        free_clients_(pool_config.max_connection){};
 
   template <typename T>
   async_simple::coro::Lazy<return_type<T>> send_request(
diff --git a/include/ylt/coro_io/detail/client_queue.hpp b/include/ylt/coro_io/detail/client_queue.hpp
index 42ef53bc98..06bb6aab28 100644
--- a/include/ylt/coro_io/detail/client_queue.hpp
+++ b/include/ylt/coro_io/detail/client_queue.hpp
@@ -15,7 +15,6 @@
  */
 #pragma once
 #include <atomic>
-#include <iterator>
 
 #include "ylt/util/concurrentqueue.h"
 namespace coro_io::detail {
@@ -49,9 +48,7 @@ class client_queue {
       : queue_{moodycamel::ConcurrentQueue<client_t>{reserve_size},
                moodycamel::ConcurrentQueue<client_t>{reserve_size}} {};
   std::size_t size() const noexcept { return size_[0] + size_[1]; }
-  void reselect() noexcept {
-    const int_fast16_t index = (selected_index_ ^= 1);
-  }
+  void reselect() noexcept { selected_index_ ^= 1; }
   std::size_t enqueue(client_t&& c) {
     const int_fast16_t index = selected_index_;
     auto cnt = ++size_[index];
@@ -77,7 +74,7 @@ class client_queue {
     }
     return false;
   }
-  std::size_t clear_old(int max_clear_cnt) {
+  std::size_t clear_old(std::size_t max_clear_cnt) {
     const int_fast16_t index = selected_index_ ^ 1;
     if (size_[index]) {
       std::size_t result =
diff --git a/include/ylt/coro_io/io_context_pool.hpp b/include/ylt/coro_io/io_context_pool.hpp
index 2f9cd5cc2c..a740b0392b 100644
--- a/include/ylt/coro_io/io_context_pool.hpp
+++ b/include/ylt/coro_io/io_context_pool.hpp
@@ -193,7 +193,7 @@ class multithread_context_pool {
   ~multithread_context_pool() { stop(); }
 
   void run() {
-    for (int i = 0; i < thd_num_; i++) {
+    for (std::size_t i = 0; i < thd_num_; i++) {
       thds_.emplace_back([this] {
         ioc_.run();
       });
diff --git a/include/ylt/util/meta_string.hpp b/include/ylt/util/meta_string.hpp
index ecd53f05bd..9b3bad9e66 100644
--- a/include/ylt/util/meta_string.hpp
+++ b/include/ylt/util/meta_string.hpp
@@ -130,7 +130,7 @@ struct meta_string {
     constexpr size_t n = substr_len(pos, count);
 
     meta_string<n> result;
-    for (int i = 0; i < n; ++i) {
+    for (std::size_t i = 0; i < n; ++i) {
       result[i] = elements_[pos + i];
     }
     return result;
diff --git a/src/coro_io/tests/test_channel.cpp b/src/coro_io/tests/test_channel.cpp
index 9642562660..836e049e4b 100644
--- a/src/coro_io/tests/test_channel.cpp
+++ b/src/coro_io/tests/test_channel.cpp
@@ -79,9 +79,8 @@ TEST_CASE("test single host") {
     auto channel = coro_io::channel<coro_rpc::coro_rpc_client>::create(hosts);
     for (int i = 0; i < 100; ++i) {
       auto res = co_await channel.send_request(
-          [&i, &hosts](
-              coro_rpc::coro_rpc_client &client,
-              std::string_view host) -> async_simple::coro::Lazy<void> {
+          [&hosts](coro_rpc::coro_rpc_client &client,
+                   std::string_view host) -> async_simple::coro::Lazy<void> {
             CHECK(host == hosts[0]);
             co_return;
           });