diff --git a/include/xemmai/engine.h b/include/xemmai/engine.h
index 01c59414..96329ee7 100644
--- a/include/xemmai/engine.h
+++ b/include/xemmai/engine.h
@@ -32,7 +32,7 @@ class t_engine
 	friend class t_symbol;
 	friend struct t_code;
 	friend struct t_safe_region;
-	friend XEMMAI__PORTABLE__EXPORT t_engine* f_engine();
+	friend t_engine* f_engine();
 
 public:
 	struct t_options
diff --git a/include/xemmai/global.h b/include/xemmai/global.h
index 93d83d1e..52d80387 100644
--- a/include/xemmai/global.h
+++ b/include/xemmai/global.h
@@ -18,7 +18,7 @@ class t_global : public t_library
 {
 	friend struct t_type_of<t_map>;
 	friend class t_engine;
-	friend XEMMAI__PORTABLE__EXPORT t_global* f_global();
+	friend t_global* f_global();
 
 	static inline XEMMAI__PORTABLE__THREAD t_global* v_instance;
 
@@ -235,7 +235,9 @@ XEMMAI__LIBRARY__TYPE(t_global, bytes)
 XEMMAI__LIBRARY__TYPE_AS(t_global, t_lexer::t_error, lexer__error)
 XEMMAI__LIBRARY__TYPE_AS(t_global, t_parser::t_error, parser__error)
 
-#ifndef _WIN32
+#ifdef _WIN32
+XEMMAI__PORTABLE__EXPORT t_global* f_global();
+#else
 inline t_global* f_global()
 {
 	return t_global::v_instance;
diff --git a/include/xemmai/type.h b/include/xemmai/type.h
index 39182671..ab68e593 100644
--- a/include/xemmai/type.h
+++ b/include/xemmai/type.h
@@ -324,8 +324,8 @@ void f_throw_type_error [[noreturn]] (const wchar_t* a_name)
 	f_throw_type_error(typeid(typename t_fundamental<T>::t_type), a_name);
 }
 
-template<typename T>
-inline void f_check(const t_value<auto>& a_object, const wchar_t* a_name)
+template<typename T, typename T_tag>
+inline void f_check(const t_value<T_tag>& a_object, const wchar_t* a_name)
 {
 	if (!f_is<T>(a_object)) [[unlikely]] f_throw_type_error<T>(a_name);
 }
diff --git a/include/xemmai/value.h b/include/xemmai/value.h
index 160df7be..0fa0e765 100644
--- a/include/xemmai/value.h
+++ b/include/xemmai/value.h
@@ -249,7 +249,7 @@ class t_value : public T_tag
 		double v_float;
 	};
 
-	void f_copy(const t_value<auto>& a_value)
+	void f_copy(const auto& a_value)
 	{
 		if (sizeof(double) > sizeof(intptr_t))
 			v_float = a_value.v_float;
@@ -273,7 +273,8 @@ class t_value : public T_tag
 	{
 		f_copy(a_value);
 	}
-	t_value(const t_value<auto>& a_value) : T_tag(a_value)
+	template<typename T>
+	t_value(const t_value<T>& a_value) : T_tag(a_value)
 	{
 		f_copy(a_value);
 	}
@@ -284,7 +285,8 @@ class t_value : public T_tag
 		f_copy(a_value);
 		return *this;
 	}
-	t_value& operator=(const t_value<auto>& a_value)
+	template<typename T>
+	t_value& operator=(const t_value<T>& a_value)
 	{
 		static_cast<T_tag&>(*this) = a_value;
 		f_copy(a_value);