diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 5482c51..68b4fc2 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -13,6 +13,8 @@ add_library(solanaceae_message3
 	./solanaceae/message3/registry_message_model.hpp
 	./solanaceae/message3/registry_message_model.cpp
 
+	./solanaceae/message3/contact_components.hpp
+
 	./solanaceae/message3/message_time_sort.hpp
 	./solanaceae/message3/message_time_sort.cpp
 
diff --git a/src/solanaceae/message3/contact_components.hpp b/src/solanaceae/message3/contact_components.hpp
new file mode 100644
index 0000000..1dce88d
--- /dev/null
+++ b/src/solanaceae/message3/contact_components.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <solanaceae/message3/registry_message_model.hpp>
+
+#include <functional>
+
+namespace Contact::Components {
+
+	struct MessageIsSame {
+		std::function<bool(Message3Handle lh, Message3Handle rh)> comp;
+	};
+
+} // Contact::Components
+