diff --git a/ChangeLog b/ChangeLog
index 5c2fbbb..b59e315 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
 = mbed TLS 2.x.x branch released xxxx-xx-xx
 
 Bugfix
+   * Fix 1-byte buffer overflow in mbedtls_mpi_write_string() when
+     used with negative inputs. Found by Guido Vranken in #2404.
    * Fix a compilation issue with mbedtls_ecp_restart_ctx not being defined
      when MBEDTLS_ECP_ALT is defined. Reported by jwhui. Fixes #2242.
    * Run the AD too long test only if MBEDTLS_CCM_ALT is not defined.