diff --git a/ChangeLog b/ChangeLog
index 7dd3769..c5ca2fa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -47,6 +47,7 @@
 Changes
    * Avoid shadowing of time and index functions through mbed TLS function
      arguments. Found by inestlerode. Fixes #557.
+   * Improve documentation of PKCS1 decryption functions.
 
 = mbed TLS 2.1.8 branch released 2017-06-21