diff --git a/include/crow/http_connection.h b/include/crow/http_connection.h
index d3811ff66..d08bcdda6 100644
--- a/include/crow/http_connection.h
+++ b/include/crow/http_connection.h
@@ -407,7 +407,7 @@ namespace crow
                 do_write_general();
             }
 
-            queue_length -= 1;
+            queue_length--;
         }
 
     private:
diff --git a/include/crow/http_server.h b/include/crow/http_server.h
index ac3315bf1..2fd600995 100644
--- a/include/crow/http_server.h
+++ b/include/crow/http_server.h
@@ -182,7 +182,7 @@ namespace crow
             int min_queue_idx = 0;
 
             // TODO improve load balancing
-            for (uint i = 1; i < task_queue_length_pool_.size(); i += 1)
+            for (uint16_t i = 1; i < task_queue_length_pool_.size(); i++)
             {
                 if (task_queue_length_pool_[i] < task_queue_length_pool_[min_queue_idx])
                     min_queue_idx = i;
@@ -194,10 +194,12 @@ namespace crow
         {
             int service_idx = pick_io_service_idx();
             asio::io_service& is = *io_service_pool_[service_idx];
+            task_queue_length_pool_[service_idx]++;
+
             auto p = new Connection<Adaptor, Handler, Middlewares...>(
               is, handler_, server_name_, middlewares_,
               get_cached_date_str_pool_[service_idx], *task_timer_pool_[service_idx], adaptor_ctx_, task_queue_length_pool_[service_idx]);
-            task_queue_length_pool_[service_idx] += 1;
+
             acceptor_.async_accept(
               p->socket(),
               [this, p, &is](boost::system::error_code ec) {
@@ -210,6 +212,7 @@ namespace crow
                   }
                   else
                   {
+                      task_queue_length_pool_[service_idx]--;
                       delete p;
                   }
                   do_accept();
@@ -221,7 +224,7 @@ namespace crow
         std::vector<std::unique_ptr<asio::io_service>> io_service_pool_;
         std::vector<detail::task_timer*> task_timer_pool_;
         std::vector<std::function<std::string()>> get_cached_date_str_pool_;
-        std::vector<int> task_queue_length_pool_;
+        std::vector<std::atomic<uint>> task_queue_length_pool_;
         tcp::acceptor acceptor_;
         boost::asio::signal_set signals_;
         boost::asio::deadline_timer tick_timer_;