diff --git a/source/mijin/util/variant.hpp b/source/mijin/util/variant.hpp
index 42d6df1..a3a98d5 100644
--- a/source/mijin/util/variant.hpp
+++ b/source/mijin/util/variant.hpp
@@ -4,6 +4,9 @@
 #if !defined(MIJIN_UTIL_VARIANT_HPP_INCLUDED)
 #define MIJIN_UTIL_VARIANT_HPP_INCLUDED 1
 
+#include <variant>
+#include "./traits.hpp"
+
 namespace mijin
 {