diff --git a/Gemfile b/Gemfile
index d367821b..227db57c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -30,7 +30,6 @@ source 'https://rubygems.org' do
   # Redmine extensions
   unless %w(easyproject easy_gantt).any? { |plugin| Dir.exist?(File.expand_path("../../#{plugin}", __FILE__)) }
     gem 'redmine_extensions', '~> 0.3.9'
-    gem 'rubyzip', '>= 1.1.3'
 
     group :test do
       gem 'rails-controller-testing'
diff --git a/init.rb b/init.rb
index 4afc5bef..8a0fded7 100644
--- a/init.rb
+++ b/init.rb
@@ -35,7 +35,7 @@ Redmine::Plugin.register :redmine_dmsf do
   description 'Document Management System Features'
   version '2.4.6 devel'
   
-  requires_redmine version_or_higher: '4.0.0'
+  requires_redmine version_or_higher: '4.2.0'
 
   settings partial: 'settings/dmsf_settings',
             default: {