Adds referene in ChangeLog for issue #1623
diff --git a/ChangeLog b/ChangeLog
index 46d60e1..4940016 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,7 +6,7 @@
    * Change the shebang line in Perl scripts to look up perl in the PATH.
      Contributed by fbrosson in #1533.
    * Fix a memory leak in mbedtls_x509_csr_parse(), found by catenacyber,
-     Philippe Antoine.
+     Philippe Antoine. Fixes #1623.
    * Clarify documentation for mbedtls_ssl_write() to include 0 as a valid
      return value. Found by @davidwu2000. #839
    * Fix the key_app_writer example which was writing a leading zero byte which