diff --git a/topics/basics/plugin_structure/plugin_extensions.md b/topics/basics/plugin_structure/plugin_extensions.md
index 08437aaa1..4835be7f6 100644
--- a/topics/basics/plugin_structure/plugin_extensions.md
+++ b/topics/basics/plugin_structure/plugin_extensions.md
@@ -79,6 +79,7 @@ Please note the following important points:
 - Extension implementation must be stateless. Use explicit [](plugin_services.md) for managing (runtime) data.
 - Avoid any initialization in the constructor, see also notes for [Services](plugin_services.md#constructor).
 - Do not perform any static initialization. Use inspection <control>Plugin DevKit | Code | Static initialization in extension point implementations</control> (2023.3).
+- An extension implementation must not be registered as [Service](plugin_services.md) additionally. Use inspection <control>Plugin DevKit | Code | Extension registered as service/component</control> (2023.3).
 
 When using [Kotlin](using_kotlin.md):