diff --git a/ChangeLog b/ChangeLog
index 6ba9a5a..70488e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -73,6 +73,8 @@
 Changes
    * Add unit tests for AES-GCM when called through mbedtls_cipher_auth_xxx()
      from the cipher abstraction layer. Fixes #2198.
+   * Clarify how the interface of the CTR_DRBG module relates to
+     NIST SP 800-90A.
 
 = mbed TLS 2.16.3 branch released 2019-09-06