diff --git a/CHANGES.txt b/CHANGES.txt
index 4fa0ac73661d..f9d694a7c491 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -2,6 +2,10 @@
   Kotlin
   * Fix duplicate class error (#8653)
 
+  PHP
+  * Fixed SEGV in sub-message getters for well-known types when message is unset
+    (#8670)
+
 2021-05-07 version 3.17.1 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
   PHP
   * Fixed PHP memory leaks and arginfo errors. (#8614)