diff --git a/ChangeLog b/ChangeLog
index fd51363b95..9863d27343 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Mar 14 11:53:01 2013  Narihiro Nakamura  <authornari@gmail.com>
+
+	* NEWS: describe RUBY_HEAP_SLOTS_GROWTH_FACTOR.
+
 Thu Mar 14 10:01:12 2013  Eric Hodel  <drbrain@segment7.net>
 
 	* doc/globals.rdoc:  $? is thread-local
diff --git a/NEWS b/NEWS
index 18e145bd60..c77c427c32 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,10 @@ with all sufficient information, see the ChangeLog file.
 === Language changes
 === Core classes updates (outstanding ones only)
 
+* GC
+  * added environment variable:
+    * RUBY_HEAP_SLOTS_GROWTH_FACTOR: growth rate of the heap.
+
 * Mutex
   * misc
     * Mutex#owned? is no longer experimental.