diff --git a/NEWS.md b/NEWS.md
index e673578..710198a 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -6,6 +6,12 @@
 
 * adds `partial_metadata_format` to support Docker 20.10 journald log driver improvements [moby/moby#41407](https://github.com/moby/moby/pull/41407) 
 
+## v2.6.0
+
+### Improvements
+
+* Support `buffer_limit_size`, `buffer_overflow_method` to change behavior when buffer overflow. See #68
+
 ## v2.3.0
 
 ### Improvements
diff --git a/fluent-plugin-concat.gemspec b/fluent-plugin-concat.gemspec
index ac60c2c..fa83a75 100644
--- a/fluent-plugin-concat.gemspec
+++ b/fluent-plugin-concat.gemspec
@@ -4,7 +4,7 @@ $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 
 Gem::Specification.new do |spec|
   spec.name          = "fluent-plugin-concat"
-  spec.version       = "2.5.0"
+  spec.version       = "2.6.0"
   spec.authors       = ["Kenji Okimoto"]
   spec.email         = ["okimoto@clear-code.com"]