diff --git a/ChangeLog b/ChangeLog
index 0a60f70fe..d0bd37736 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,12 +3,12 @@ mbed TLS ChangeLog (Sorted per branch, date)
 = mbed TLS x.x.x branch released xxxx-xx-xx
 
 API Changes
-   * Extend the platform module with an abstraction mbedtls_platform_gmtime()
+   * Extend the platform module with an abstraction mbedtls_platform_gmtime_r()
      whose implementation should behave as a thread safe version of gmtime().
      This allows users to configure such an implementation at compile time when
-     the target system cannot be deduced automatically. At this stage Mbed TLS
-     is only able to automatically select implementations for Windows and POSIX
-     C libraries.
+     the target system cannot be deduced automatically, by setting the option
+     MBEDTLS_PLATFORM_GMTIME_R_ALT. At this stage Mbed TLS is only able to
+     automatically select implementations for Windows and POSIX C libraries.
 
 Bugfix
    * Fixes an issue with MBEDTLS_CHACHAPOLY_C which would not compile if