diff --git a/ChangeLog b/ChangeLog
index f66bbb417c..8acc5cac4d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed May 14 18:03:28 2014  Koichi Sasada  <ko1@atdot.net>
+
+	* gc.c: enable RGENGC_AGE2_PROMOTION.
+
 Wed May 14 18:02:30 2014  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (rgengc_rememberset_mark): promote remembered object earlier.
diff --git a/gc.c b/gc.c
index c9d4efa966..abac6b9910 100644
--- a/gc.c
+++ b/gc.c
@@ -215,7 +215,7 @@ static ruby_gc_params_t gc_params = {
  * 1: Infant gen -> Young -> Old gen
  */
 #ifndef RGENGC_AGE2_PROMOTION
-#define RGENGC_AGE2_PROMOTION 0
+#define RGENGC_AGE2_PROMOTION 1
 #endif
 
 /* RGENGC_ESTIMATE_OLDMALLOC