diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 044cfc07bce9b1..6aed8d2b5f984d 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -500,6 +500,9 @@ Reedy in :issue:`40468`.)  Move the indent space setting from the Font tab to
 the new Windows tab.  (Contributed by Mark Roseman and Terry Jan Reedy in
 :issue:`33962`.)
 
+Apply syntax highlighting to `.pyi` files. (Contributed by Alex
+Waygood and Terry Jan Reedy in :issue:`45447`.)
+
 imaplib
 -------