Clarified Changelog for fix #602
diff --git a/ChangeLog b/ChangeLog
index 420f285..5270685 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -20,7 +20,7 @@
      builds where the configuration MBEDTLS_PEM_WRITE_C is not defined. Found
      by inestlerode. #559.
    * Fix documentation and implementation missmatch for function arguments of
-     mbedtls_gcm_finish(). Found by cmiatpaar.
+     mbedtls_gcm_finish(). Found by cmiatpaar. #602
 
 = mbed TLS 2.1.5 branch released 2016-06-28