diff --git a/CHANGES.rst b/CHANGES.rst
index 78ea473da..a167b30eb 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -20,7 +20,11 @@ development at the same time, such as 4.5.x and 5.0.
 Unreleased
 ----------
 
-Nothing yet.
+- Internal debugging data added to sys.modules is now an actual module, to
+  avoid confusing code that examines everything in sys.modules.  Thanks,
+  Yilei Yang (`pull 1399`_).
+
+.. _pull 1399: https://github.com/nedbat/coveragepy/pull/1399
 
 
 .. _changes_6-4-1:
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index ef1505742..2e4ed85b3 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -153,6 +153,7 @@ Valentin Lab
 Vince Salvino
 Ville Skyttä
 Xie Yanbo
+Yilei "Dolee" Yang
 Yury Selivanov
 Zac Hatfield-Dodds
 Zooko Wilcox-O'Hearn