diff --git a/ChangeLog b/ChangeLog
index b85f9d1bf..d13e9ce99 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -19,6 +19,7 @@ Features
 Bugfix
    * Remove macros from compat-1.3.h that correspond to deleted items from most
      recent versions of the library. Found by Kyle Keen.
+   * Fixed issue in mutexes to failing to initialise. #667
 
 = mbed TLS 2.4.2 branch released 2017-03-08