add changelog for #300
diff --git a/CHANGES.txt b/CHANGES.txt
index 701c2b0..c40246b 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,3 +1,14 @@
+Unreleased
+----------
+
+- Fix an issue with keep-alive connections in which memory usage was higher
+ than expected because output buffers were being reused across requests on
+ a long-lived connection and each buffer would not be freed until it was full
+ or the connection was closed. Buffers are now rotated per-request to
+ stabilize their behavior.
+
+ See https://github.com/Pylons/waitress/pull/300
+
1.4.3 (2020-02-02)
------------------
