diff --git a/NEWS b/NEWS
index 557c7bad9e..4bfca9240c 100644
--- a/NEWS
+++ b/NEWS
@@ -141,6 +141,9 @@ with all sufficient information, see the ChangeLog file or Redmine
 * Random.raw_seed renamed to become Random.urandom.  It is now
   applicable to non-seeding purposes due to [Bug #9569].
 
+* ConditionVariable, Queue and SizedQueue reimplemented for speed.
+  They no longer subclass Struct. [Feature #13552]
+
 === Stdlib compatibility issues (excluding feature bug fixes)
 
 * mathn.rb
@@ -157,6 +160,8 @@ with all sufficient information, see the ChangeLog file or Redmine
 
 * SecureRandom now prefers OS-provided sources than OpenSSL. [Bug #9569]
 
+* Mutex rewritten to be smaller and faster [Feature #13517]
+
 === Miscellaneous changes
 
 * Print backtrace and error message in reverse order if STDERR is unchanged and a tty.