diff --git a/docs/source/design.rst b/docs/source/design.rst
index 21213e8a1..28f6f061e 100644
--- a/docs/source/design.rst
+++ b/docs/source/design.rst
@@ -519,4 +519,6 @@ Mnesia/ETS Tables
 +--------------------+--------+----------------------------------------+
 | mqtt_client        | ets    | Client Table                           |
 +--------------------+--------+----------------------------------------+
+| mqtt_retained      | mnesia | Retained Message Table                 |
++--------------------+--------+----------------------------------------+