diff --git a/src/solanaceae/message3/message_serializer.hpp b/src/solanaceae/message3/message_serializer.hpp
index 65d342d..a3024e1 100644
--- a/src/solanaceae/message3/message_serializer.hpp
+++ b/src/solanaceae/message3/message_serializer.hpp
@@ -11,6 +11,8 @@ struct MessageSerializerNJ {
 	using Registry = Message3Registry;
 	using Handle = Message3Handle;
 
+	static constexpr const char* version {"1"};
+
 	Contact3Registry& cr;
 
 	// nlohmann