diff --git a/ChangeLog b/ChangeLog
index 2bf83a34e0..cc1cacd9ac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Sep  7 14:50:01 2016  Kazuki Tsujimoto  <kazuki@callcc.net>
+
+	* gems/bundled_gems: update to power_assert 0.3.1.
+
 Wed Sep  7 12:16:09 2016  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
 
 	* ext/psych/*, test/psych/*: Update psych-2.1.1
diff --git a/gems/bundled_gems b/gems/bundled_gems
index 1bbec050bc..8f2ae40607 100644
--- a/gems/bundled_gems
+++ b/gems/bundled_gems
@@ -1,4 +1,4 @@
-power_assert 0.3.0
+power_assert 0.3.1
 test-unit 3.2.1
 minitest 5.9.0
 rake 11.2.2