diff --git a/include/rexy/threadpool.hpp b/include/rexy/threadpool.hpp
index 70ba8f8..130a02f 100644
--- a/include/rexy/threadpool.hpp
+++ b/include/rexy/threadpool.hpp
@@ -1,6 +1,6 @@
 /**
 	This file is a part of rexy's general purpose library
-	Copyright (C) 2020 rexy712
+	Copyright (C) 2020-2022 rexy712
 
 	This program is free software: you can redistribute it and/or modify
 	it under the terms of the GNU General Public License as published by
@@ -29,6 +29,7 @@
 #include <future> //future, packaged_task
 #include <functional> //function, bind
 #include <utility> //move, forward
+#include <type_traits> //invoke_result_t
 
 #include "rexy.hpp"
 
@@ -62,14 +63,14 @@ namespace rexy{
 		void invalidate(void);
 
 		template<class Func, class... Args>
-		auto add_job(Func&& f, Args&&... args) -> std::future<decltype(std::forward<Func>(f)(std::forward<Args>(args)...))>;
+		auto add_job(Func&& f, Args&&... args) -> std::future<std::invoke_result_t<Func,Args...>>;
 
 	private:
 		void worker_loop(void);
 	};
 
 	template<class Func, class... Args>
-	auto threadpool::add_job(Func&& f, Args&&... args) -> std::future<decltype(std::forward<Func>(f)(std::forward<Args>(args)...))>{
+	auto threadpool::add_job(Func&& f, Args&&... args) -> std::future<std::invoke_result_t<Func,Args...>>{
 		using return_t = decltype(std::forward<Func>(f)(std::forward<Args>(args)...));
 		using task_t = std::packaged_task<return_t(void)>;