diff --git a/cpp/types.hpp b/cpp/types.hpp
index e6d7433..5f7d138 100644
--- a/cpp/types.hpp
+++ b/cpp/types.hpp
@@ -43,6 +43,28 @@ typedef unsigned __int128 rk_ullong;
 typedef float rk_float;
 typedef void * rk_handle_t;
 
-#define RK_INVALID_HANDLE nullptr
+static_assert(sizeof(rk_char) == 1);
+static_assert(sizeof(rk_wchar) == 4);
+static_assert(sizeof(rk_float) == 4);
+
+#pragma pack(push, 4)
+
+template<bool _signed, unsigned _cols>
+struct rk_packed {
+};
+
+template<unsigned _cols>
+struct alignas(alignof(rk_int)) rk_packed<true, _cols> {
+    typedef rk_int type;
+    rk_int packed;
+};
+
+template<unsigned _cols>
+struct alignas(alignof(rk_uint)) rk_packed<false, _cols> {
+    typedef rk_uint type;
+    rk_uint packed;
+};
+
+#pragma pack(pop)
 
 #endif // _RK_ENGINE_TYPES_H