diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5162735..328bcf3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-# 3.8 version is required for `cxx_std_14`
+# 3.8 version is required for `cxx_std_11`
 cmake_minimum_required(VERSION 3.8 FATAL_ERROR)
 
 if(NOT DEFINED PROJECT_NAME)
@@ -8,7 +8,7 @@ endif()
 project(invoke.hpp)
 
 add_library(${PROJECT_NAME} INTERFACE)
-target_compile_features(${PROJECT_NAME} INTERFACE cxx_std_14)
+target_compile_features(${PROJECT_NAME} INTERFACE cxx_std_11)
 target_include_directories(${PROJECT_NAME} INTERFACE headers)
 
 if(BUILD_AS_STANDALONE)
diff --git a/README.md b/README.md
index 94a7c03..ee5c829 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # invoke.hpp
 
-> std::invoke/std::apply analogs for C++14
+> std::invoke/std::apply analogs for C++11/14
 
 [![travis][badge.travis]][travis]
 [![appveyor][badge.appveyor]][appveyor]
@@ -12,14 +12,14 @@
 [badge.travis]: https://img.shields.io/travis/BlackMATov/invoke.hpp/master.svg?logo=travis
 [badge.appveyor]: https://img.shields.io/appveyor/ci/BlackMATov/invoke-hpp/master.svg?logo=appveyor
 [badge.codecov]: https://img.shields.io/codecov/c/github/BlackMATov/invoke.hpp/master.svg?logo=codecov
-[badge.language]: https://img.shields.io/badge/language-C%2B%2B14-red.svg
+[badge.language]: https://img.shields.io/badge/language-C%2B%2B11-red.svg
 [badge.license]: https://img.shields.io/badge/license-MIT-blue.svg
 [badge.paypal]: https://img.shields.io/badge/donate-PayPal-orange.svg?logo=paypal&colorA=00457C
 
 [travis]: https://travis-ci.org/BlackMATov/invoke.hpp
 [appveyor]: https://ci.appveyor.com/project/BlackMATov/invoke-hpp
 [codecov]: https://codecov.io/gh/BlackMATov/invoke.hpp
-[language]: https://en.wikipedia.org/wiki/C%2B%2B14
+[language]: https://en.wikipedia.org/wiki/C%2B%2B11
 [license]: https://en.wikipedia.org/wiki/MIT_License
 [paypal]: https://www.paypal.me/matov
 
diff --git a/headers/invoke.hpp/invoke.hpp b/headers/invoke.hpp/invoke.hpp
index 8dfb861..5bd950e 100644
--- a/headers/invoke.hpp/invoke.hpp
+++ b/headers/invoke.hpp/invoke.hpp
@@ -11,9 +11,6 @@
 #include <functional>
 #include <type_traits>
 
-#define INVOKE_HPP_NOEXCEPT_RETURN(...) \
-    noexcept(noexcept(__VA_ARGS__)) { return __VA_ARGS__; }
-
 #define INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(...) \
     noexcept(noexcept(__VA_ARGS__)) -> decltype (__VA_ARGS__) { return __VA_ARGS__; }
 
@@ -35,6 +32,42 @@ namespace invoke_hpp
     using void_t = typename impl::make_void<Args...>::type;
 }
 
+//
+// integer_sequence
+//
+
+namespace invoke_hpp
+{
+    template < typename T, T... Ints >
+    struct integer_sequence {
+        using value_type = T;
+        static constexpr std::size_t size() noexcept { return sizeof...(Ints); }
+    };
+
+    template < std::size_t... Ints >
+    using index_sequence = integer_sequence<std::size_t, Ints...>;
+
+    namespace impl
+    {
+        template < typename T, std::size_t N, T... Ints >
+        struct make_integer_sequence_impl
+        : make_integer_sequence_impl<T, N - 1, N - 1, Ints...> {};
+
+        template < typename T, T... Ints >
+        struct make_integer_sequence_impl<T, 0, Ints...>
+        : integer_sequence<T, Ints...> {};
+    }
+
+    template < typename T, std::size_t N >
+    using make_integer_sequence = impl::make_integer_sequence_impl<T, N>;
+
+    template < std::size_t N >
+    using make_index_sequence = make_integer_sequence<std::size_t, N>;
+
+    template < typename... Ts >
+    using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
+}
+
 //
 // is_reference_wrapper
 //
@@ -54,7 +87,7 @@ namespace invoke_hpp
 
     template < typename T >
     struct is_reference_wrapper
-    : impl::is_reference_wrapper_impl<std::remove_cv_t<T>> {};
+    : impl::is_reference_wrapper_impl<typename std::remove_cv<T>::type> {};
 }
 
 //
@@ -72,7 +105,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Derived,
-            typename std::enable_if_t<std::is_base_of<Base, std::decay_t<Derived>>::value, int> = 0
+            typename std::enable_if<std::is_base_of<Base, typename std::decay<Derived>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_object_impl(F Base::* f, Derived&& ref)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -81,7 +114,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename RefWrap,
-            typename std::enable_if_t<is_reference_wrapper<std::decay_t<RefWrap>>::value, int> = 0
+            typename std::enable_if<is_reference_wrapper<typename std::decay<RefWrap>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_object_impl(F Base::* f, RefWrap&& ref)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -90,10 +123,10 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Pointer,
-            typename std::enable_if_t<
-                !std::is_base_of<Base, std::decay_t<Pointer>>::value &&
-                !is_reference_wrapper<std::decay_t<Pointer>>::value
-            , int> = 0
+            typename std::enable_if<
+                !std::is_base_of<Base, typename std::decay<Pointer>::type>::value &&
+                !is_reference_wrapper<typename std::decay<Pointer>::type>::value
+            , int>::type = 0
         >
         constexpr auto invoke_member_object_impl(F Base::* f, Pointer&& ptr)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -106,7 +139,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Derived, typename... Args,
-            typename std::enable_if_t<std::is_base_of<Base, std::decay_t<Derived>>::value, int> = 0
+            typename std::enable_if<std::is_base_of<Base, typename std::decay<Derived>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_function_impl(F Base::* f, Derived&& ref, Args&&... args)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -115,7 +148,7 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename RefWrap, typename... Args,
-            typename std::enable_if_t<is_reference_wrapper<std::decay_t<RefWrap>>::value, int> = 0
+            typename std::enable_if<is_reference_wrapper<typename std::decay<RefWrap>::type>::value, int>::type = 0
         >
         constexpr auto invoke_member_function_impl(F Base::* f, RefWrap&& ref, Args&&... args)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -124,10 +157,10 @@ namespace invoke_hpp
         template
         <
             typename Base, typename F, typename Pointer, typename... Args,
-            typename std::enable_if_t<
-                !std::is_base_of<Base, std::decay_t<Pointer>>::value &&
-                !is_reference_wrapper<std::decay_t<Pointer>>::value
-            , int> = 0
+            typename std::enable_if<
+                !std::is_base_of<Base, typename std::decay<Pointer>::type>::value &&
+                !is_reference_wrapper<typename std::decay<Pointer>::type>::value
+            , int>::type = 0
         >
         constexpr auto invoke_member_function_impl(F Base::* f, Pointer&& ptr, Args&&... args)
         INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -137,7 +170,7 @@ namespace invoke_hpp
     template
     <
         typename F, typename... Args,
-        typename std::enable_if_t<!std::is_member_pointer<std::decay_t<F>>::value, int> = 0
+        typename std::enable_if<!std::is_member_pointer<typename std::decay<F>::type>::value, int>::type = 0
     >
     constexpr auto invoke(F&& f, Args&&... args)
     INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -146,7 +179,7 @@ namespace invoke_hpp
     template
     <
         typename F, typename T,
-        typename std::enable_if_t<std::is_member_object_pointer<std::decay_t<F>>::value, int> = 0
+        typename std::enable_if<std::is_member_object_pointer<typename std::decay<F>::type>::value, int>::type = 0
     >
     constexpr auto invoke(F&& f, T&& t)
     INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -155,7 +188,7 @@ namespace invoke_hpp
     template
     <
         typename F, typename... Args,
-        typename std::enable_if_t<std::is_member_function_pointer<std::decay_t<F>>::value, int> = 0
+        typename std::enable_if<std::is_member_function_pointer<typename std::decay<F>::type>::value, int>::type = 0
     >
     constexpr auto invoke(F&& f, Args&&... args)
     INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
@@ -205,10 +238,10 @@ namespace invoke_hpp
 
         template < typename R, typename F, typename... Args >
         struct is_invocable_r_impl<void_t<is_invocable_r_impl_tag, invoke_result_t<F, Args...>>, R, F, Args...>
-        : std::conditional_t<
+        : std::conditional<
             std::is_void<R>::value,
             std::true_type,
-            std::is_convertible<invoke_result_t<F, Args...>, R>> {};
+            std::is_convertible<invoke_result_t<F, Args...>, R>>::type {};
     }
 
     template < typename R, typename F, typename... Args >
@@ -228,21 +261,20 @@ namespace invoke_hpp
     namespace impl
     {
         template < typename F, typename Tuple, std::size_t... I >
-        constexpr decltype(auto) apply_impl(F&& f, Tuple&& args, std::index_sequence<I...>)
-        INVOKE_HPP_NOEXCEPT_RETURN(
+        constexpr auto apply_impl(F&& f, Tuple&& args, index_sequence<I...>)
+        INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
             invoke_hpp::invoke(
                 std::forward<F>(f),
                 std::get<I>(std::forward<Tuple>(args))...))
     }
 
     template < typename F, typename Tuple >
-    constexpr decltype(auto) apply(F&& f, Tuple&& args)
-    INVOKE_HPP_NOEXCEPT_RETURN(
+    constexpr auto apply(F&& f, Tuple&& args)
+    INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN(
         impl::apply_impl(
             std::forward<F>(f),
             std::forward<Tuple>(args),
-            std::make_index_sequence<std::tuple_size<std::decay_t<Tuple>>::value>()))
+            make_index_sequence<std::tuple_size<typename std::decay<Tuple>::type>::value>()))
 }
 
-#undef INVOKE_HPP_NOEXCEPT_RETURN
 #undef INVOKE_HPP_NOEXCEPT_DECLTYPE_RETURN