Add ChangeLog entry for #992 fix
diff --git a/ChangeLog b/ChangeLog
index 4940016..e94dfc6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,6 +11,8 @@
      return value. Found by @davidwu2000. #839
    * Fix the key_app_writer example which was writing a leading zero byte which
      was creating an invalid ASN.1 tag. Found by Aryeh R. Fixes #1257.
+   * Remove unused headers included in x509.c. Found by Chris Hanson and fixed
+     by Brendan Shanks. Part of a fix for #992.
 
 = mbed TLS 2.7.4 branch released 2018-06-18