diff --git a/Gemfile b/Gemfile
deleted file mode 100644
index 52a60e7..0000000
--- a/Gemfile
+++ /dev/null
@@ -1 +0,0 @@
-gem 'iconv'
diff --git a/Gemfile.lock b/Gemfile.lock
deleted file mode 100644
index 43228fe..0000000
--- a/Gemfile.lock
+++ /dev/null
@@ -1,12 +0,0 @@
-GEM
-  specs:
-    iconv (1.0.4)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  iconv
-
-BUNDLED WITH
-   1.11.2
diff --git a/lib/redmine_ruby_lang_mailing_list_customization/redmine_ext/mail_handler.rb b/lib/redmine_ruby_lang_mailing_list_customization/redmine_ext/mail_handler.rb
index 40754da..4c15315 100644
--- a/lib/redmine_ruby_lang_mailing_list_customization/redmine_ext/mail_handler.rb
+++ b/lib/redmine_ruby_lang_mailing_list_customization/redmine_ext/mail_handler.rb
@@ -1,9 +1,8 @@
-require 'iconv'
 MailHandler.class_eval do
   def dispatch_with_ruby_lang_mailing_list_customization
     if charset = email.header.charset and charset.downcase != 'utf-8'
-      email.body = Iconv.conv("UTF-8", charset, email.body) rescue nil
-      email.subject = Iconv.conv("UTF-8", charset, email.subject) rescue nil
+      email.body = email.body.encode("UTF-8", charset) rescue nil
+      email.subject = email.subject.encode("UTF-8", charset) rescue nil
     end
     email.subject = email.subject.sub(/\[#{Regexp.escape driver.mailing_list.identifier}:\d+\]/, '')
     if subject_tag_re =~ email.subject