diff --git a/.travis.yml b/.travis.yml
index 523d164..3e1b432 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,9 @@
 language: ruby
 
-jdk: oraclejdk8
+dist: trusty
+
+jdk: openjdk8
+
 sudo: false
 
 addons:
@@ -15,9 +18,9 @@ before_install:
     ruby -v
     rvm get head
     rvm use jruby-9.0.5.0 --install
-    gem install bundler
+    gem install bundler -v '< 2'
     ruby -v
-  - gem i bundler
+  - gem install bundler -v '< 2'
 
 rvm:
   - jruby-9.0.5.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e3ac44f..e6e1b69 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.5.15 - 2020-01-22
+
+* [enhancement] Update the authentication method to latest [#63](https://github.com/treasure-data/embulk-input-mixpanel/pull/63)
+
 ## 0.5.14 - 2018-10-22
 
 * [enhancement] Handle the wrong period during transition from standard to daylight saving time exception [#62](https://github.com/treasure-data/embulk-input-mixpanel/pull/62)
diff --git a/README.md b/README.md
index 37a8079..bfd02b2 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,6 @@ To get it, you should log in mixpanel website, and click gear icon at the lower
 
 ### Configuration
 
-- **api_key**: project API Key (string, required)
 - **api_secret**: project API Secret (string, required)
 - **export_endpoint**: the Data Export API's endpoint (string, default to "http://data.mixpanel.com/api/2.0/export")
 - **timezone**: project timezone(string, required)
@@ -69,7 +68,6 @@ If you have such data and set config.yml as below.
 ```yaml
 in:
   type: mixpanel
-  api_key: "API_KEY"
   api_secret: "API_SECRET"
   timezone: "US/Pacific"
   from_date: "2015-07-19"
@@ -102,7 +100,6 @@ in:
 ```yaml
 in:
   type: mixpanel
-  api_key: "API_KEY"
   api_secret: "API_SECRET"
   timezone: "US/Pacific"
   from_date: "2015-07-19"
diff --git a/embulk-input-mixpanel.gemspec b/embulk-input-mixpanel.gemspec
index b59cdf5..5c2f89c 100644
--- a/embulk-input-mixpanel.gemspec
+++ b/embulk-input-mixpanel.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
   spec.name          = "embulk-input-mixpanel"
-  spec.version       = "0.5.14"
+  spec.version       = "0.5.15"
   spec.authors       = ["yoshihara", "uu59"]
   spec.summary       = "Mixpanel input plugin for Embulk"
   spec.description   = "Loads records from Mixpanel."
@@ -13,7 +13,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency 'httpclient', '>= 2.8.3' # To use tcp_keepalive
-  spec.add_dependency 'tzinfo'
+  spec.add_dependency 'tzinfo', '1.2.5' # to avoid failure in when upgrade to 1.2.6 https://github.com/tzinfo/tzinfo/issues/114
   spec.add_dependency 'perfect_retry', ["~> 0.5"]
   spec.add_dependency 'activesupport'
   spec.add_development_dependency 'bundler', ['~> 1.0']