diff --git a/tile/base/future/boxed.h b/tile/base/future/boxed.h
index 8ad461f..d168e75 100644
--- a/tile/base/future/boxed.h
+++ b/tile/base/future/boxed.h
@@ -89,7 +89,7 @@ private:
     }
 
 private:
-    std::variant<mpark::monostate, value_type> holding_;
+    mpark::variant<mpark::monostate, value_type> holding_;
 };
 
 static_assert(std::is_void<decltype(std::declval<Boxed<>>().Get())>::value, "");
@@ -110,7 +110,7 @@ RetrieveBoxed()
 
 template<typename... Ts>
 template<typename... Us, typename>
-Boxed<Ts...>::Boxed(box_values_t, Us &&...imms) : holding_(std::in_place_index_t<kValue>(), std::forward<Us>(imms)...)
+Boxed<Ts...>::Boxed(box_values_t, Us &&...imms) : holding_(mpark::in_place_index_t<kValue>(), std::forward<Us>(imms)...)
 {}
 
 template<typename... Ts>
diff --git a/tile/base/future/core.h b/tile/base/future/core.h
index e10e8db..97b4829 100644
--- a/tile/base/future/core.h
+++ b/tile/base/future/core.h
@@ -43,7 +43,7 @@ private:
 private:
     // std::mutex lock_;
     Mutex lock_;
-    std::variant<WaitingForSingleObject, Satisfied> state_;
+    mpark::variant<WaitingForSingleObject, Satisfied> state_;
     Executor executor_;
 };
 
diff --git a/tile/base/variant.h b/tile/base/variant.h
index a764f46..894971f 100644
--- a/tile/base/variant.h
+++ b/tile/base/variant.h
@@ -3,14 +3,6 @@
 
 #pragma once
 
-#if __cplusplus >= 201703L
-#include <variant>
-#else
 #include "tile/base/internal/variant.h"
 
-namespace std {
-using namespace mpark;
-}
-#endif
-
 #endif// TILE_BASE_VARIANT_H