diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f8c01cc147648a9566fab6908cf787217042045c..d0fb52ae11b7694b1750a8de4356542296b3dab5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -16,6 +16,8 @@ currently being split into a few separate parts:
   a given configuration file and show a summary. Used in the updater to ensure
   new configurations are valid before overwriting existing ones.
 - [ATxTray](ATxTray): the tray application.
+- [ATxDiagnostics](ATxDiagnostics): a command line tool to run a few tests and
+  report the results.
 - [Updater](Updater): the updater script for binaries and configuration files.
 
 Refactoring suggestions and / or pull requests are welcome!