diff --git a/CHANGELOG.md b/CHANGELOG.md
index 73043f3..ddddf2d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+# v3.1.2
+- add .gemspec required_ruby_version = '>= 2.0.0'
+
 # v3.1.1
 - [[clean] module split](https://github.com/k-ta-yamada/tee_logger/pull/14)
 
diff --git a/lib/tee_logger/version.rb b/lib/tee_logger/version.rb
index 82eb67d..24dd337 100644
--- a/lib/tee_logger/version.rb
+++ b/lib/tee_logger/version.rb
@@ -1,5 +1,5 @@
 # namespace
 module TeeLogger
   # version number
-  VERSION = '3.1.1'
+  VERSION = '3.1.2'
 end