diff --git a/RELEASE_NOTES.rst b/RELEASE_NOTES.rst
index 84a9ffd23..9d4da6142 100644
--- a/RELEASE_NOTES.rst
+++ b/RELEASE_NOTES.rst
@@ -13,6 +13,7 @@ Code that imports from the old locations will continue to work, but will raise :
 All changes
 -----------
 
+- :pull:`704`: Introduce the LPdiag tool for analyzing LP programming problems and related MPS-files.
 - Drop support for Python 3.7, which `reached end-of-life on 2023-06-27 <https://peps.python.org/pep-0537/#lifespan>`__ (:pull:`738`).
   :mod:`message_ix` now requires Python version 3.8 or greater.
 - Rename :mod:`message_ix.report` (:pull:`761`).