diff --git a/ChangeLog b/ChangeLog
index e22fdee..0407b6a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -56,6 +56,9 @@
      generated in Visual Studio 2015. Reported by Steve Valliere. #742
    * Fix a resource leak in ssl_cookie, when using MBEDTLS_THREADING_C.
      Raised and fix suggested by Alan Gillingham in the mbed TLS forum. #771
+   * Fix 1 byte buffer overflow in mbedtls_mpi_write_string() when the MPI
+     number to write in hexadecimal is negative and requires an odd number of
+     digits. Found and fixed by Guido Vranken.
 
 = mbed TLS 2.4.1 branch released 2016-12-13