diff --git a/Gemfile b/Gemfile
index 731531d..309048c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,4 +5,4 @@ gemspec
 
 gem 'fluent-plugin-elasticsearch', '~> 1.0', require: false
 gem 'aws-sdk', '~> 2', require: false
-gem 'faraday_middleware-aws-signers-v4', '>= 0.1.0, < 0.1.2', require: false
+gem 'faraday_middleware-aws-signers-v4', '>= 0.1.0', '< 0.1.2', require: false
diff --git a/lib/fluent/plugin/out_aws-elasticsearch-service.rb b/lib/fluent/plugin/out_aws-elasticsearch-service.rb
index 05d84d5..f231a7d 100644
--- a/lib/fluent/plugin/out_aws-elasticsearch-service.rb
+++ b/lib/fluent/plugin/out_aws-elasticsearch-service.rb
@@ -26,7 +26,7 @@ class AwsElasticsearchServiceOutput < ElasticsearchOutput
     #
     def get_connection_options
       raise "`endpoint` require." if @endpoint.empty?
-      
+
       hosts =
         begin
           @endpoint.map do |ep|
@@ -40,11 +40,11 @@ def get_connection_options
               :credentials => credentials(ep),
               :region => ep[:region]
             }
-            
+
             host
           end
         end
-      
+
       {
         hosts: hosts
       }
@@ -60,7 +60,7 @@ def credentials(opts)
       calback = lambda do
         credentials = nil
         unless opts[:access_key_id].empty? or opts[:secret_access_key].empty?
-          credentials = Aws::Credentials.new access_key, secret_key
+          credentials = Aws::Credentials.new opts[:access_key_id], opts[:secret_access_key]
         else
           if opts[:assume_role_arn].nil?
             credentials = Aws::SharedCredentials.new({