diff --git a/readme.txt b/readme.txt
index 93740f59a..b229819f1 100644
--- a/readme.txt
+++ b/readme.txt
@@ -110,6 +110,8 @@
 - EX:  Updated LIS302DL to 1.1.0 (backported to 18.2.1).
 - EX:  Updated LPS25H to 1.1.0 (backported to 18.2.1).
 - EX:  Updated LSM303DLHC to 1.1.0 (backported to 18.2.1).
+- HAL: Fixed USB Serial driver problem with zero-size OUT transactions
+       (bug #933)(backported to 18.2.1 and 17.6.5).
 - HAL: Fixed function mfsReadRecord() causes memory corruption because a
        buffer overflow (bug #931)(backported to 18.2.1).
 - HAL: Fixed silence GCC 7.3.0 warning (bug #930)(backported to 18.2.1