diff --git a/include/umb/message.hpp b/include/umb/message.hpp
index 8f01078..2de9c87 100644
--- a/include/umb/message.hpp
+++ b/include/umb/message.hpp
@@ -71,6 +71,9 @@ class Message
      *         message in bytes.
      */
     [[nodiscard]] virtual size_t serialized_size() const = 0;
+
+    // TODO: reconsider this API.
+    [[nodiscard]] constexpr virtual uint16_t type() const noexcept = 0;
 };
 
 }