diff --git a/README.md b/README.md
index 323db04..f920a34 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ This plugin allows Redmine users to select themes in their account settings. The
 
 ## Compatibility
 
-This plugin version is compatible only with Redmine 2.1.x and later.
+This plugin version is compatible only with Redmine 4.x and later.
 
 ## Installation
 
diff --git a/app/views/users/_user_specific_theme.html.erb b/app/views/users/_user_specific_theme.html.erb
index 258951d..fd29647 100644
--- a/app/views/users/_user_specific_theme.html.erb
+++ b/app/views/users/_user_specific_theme.html.erb
@@ -1,4 +1,6 @@
-<%= labelled_fields_for :pref, @user.pref do |pref_fields| %>
-<p><%= pref_fields.select :ui_theme, Redmine::Themes.themes.collect { |t| [t.name, t.id] },
-    { include_blank: true } %></p>
-<% end %>
+<p>
+  <%= label_tag :user_preference_attributes_ui_theme, l(:field_ui_theme) %><br>
+  <%= select_tag 'pref[ui_theme]',
+                 options_for_select(Redmine::Themes.themes.map { |theme| [theme.name, theme.id] },
+                                    @pref[:ui_theme]), include_blank: true %>
+</p>
\ No newline at end of file
diff --git a/init.rb b/init.rb
index cfd3adc..c1efaa7 100644
--- a/init.rb
+++ b/init.rb
@@ -4,10 +4,15 @@
   name        'Redmine User-Specific Theme Plugin'
   description 'This plugin allows users to set Redmine themes in the account settings.'
   author      'Restream'
-  version     '1.2.0'
+  version     '1.3.0'
   url         'https://github.com/Restream/redmine_user_specific_theme'
 
-  requires_redmine :version_or_higher => '2.1'
+  requires_redmine :version_or_higher => '4.0.0'
+
+
 end
 
-require 'redmine_user_specific_theme'
+require_relative 'lib/redmine_user_specific_theme/hooks/view_hooks'
+require_relative 'lib/redmine_user_specific_theme/patches/user_preference_patch'
+require_relative 'lib/redmine_user_specific_theme/patches/application_helper_patch'
+require_relative 'lib/redmine_user_specific_theme'
diff --git a/lib/redmine_user_specific_theme.rb b/lib/redmine_user_specific_theme.rb
index dddb229..87da07b 100644
--- a/lib/redmine_user_specific_theme.rb
+++ b/lib/redmine_user_specific_theme.rb
@@ -1,18 +1,10 @@
 module RedmineUserSpecificTheme
 end
 
-require_dependency 'redmine_user_specific_theme/hooks/view_hooks'
-require_dependency 'redmine_user_specific_theme/patches/user_preference_patch'
-require_dependency 'redmine_user_specific_theme/patches/application_helper_patch'
 
-ActionDispatch::Callbacks.to_prepare do
 
-  unless UserPreference.included_modules.include?(RedmineUserSpecificTheme::Patches::UserPreferencePatch)
-    UserPreference.send :prepend, RedmineUserSpecificTheme::Patches::UserPreferencePatch
-  end
+MyController.prepend RedmineUserSpecificTheme::Patches::UserPreferencePatch unless MyController.included_modules.include?(RedmineUserSpecificTheme::Patches::UserPreferencePatch)
 
-  unless ApplicationHelper.included_modules.include?(RedmineUserSpecificTheme::Patches::ApplicationHelperPatch)
-    ApplicationHelper.send :include, RedmineUserSpecificTheme::Patches::ApplicationHelperPatch
-  end
-
-end
+RedmineApp::Application.config.after_initialize do
+  ApplicationHelper.prepend(RedmineUserSpecificTheme::Patches::ApplicationHelperPatch)
+end
\ No newline at end of file
diff --git a/lib/redmine_user_specific_theme/patches/application_helper_patch.rb b/lib/redmine_user_specific_theme/patches/application_helper_patch.rb
index 8df0eb9..5d42d72 100644
--- a/lib/redmine_user_specific_theme/patches/application_helper_patch.rb
+++ b/lib/redmine_user_specific_theme/patches/application_helper_patch.rb
@@ -4,22 +4,18 @@ module RedmineUserSpecificTheme::Patches
   module ApplicationHelperPatch
     extend ActiveSupport::Concern
 
-    included do
-      alias_method_chain :current_theme, :user_specific
-      alias_method_chain :body_css_classes, :user_specific
-    end
-
-    def current_theme_with_user_specific
-      user_theme = Redmine::Themes.theme(User.current.pref.ui_theme)
+    def current_theme
+      user_theme = super
+      user_theme = Redmine::Themes.theme(User.current.pref.others[:ui_theme])
       user_theme || Redmine::Themes.theme(Setting.ui_theme)
     end
 
-    def body_css_classes_with_user_specific
-      css_classes = body_css_classes_without_user_specific
-      user_theme = Redmine::Themes.theme(User.current.pref.ui_theme)
+    def body_css_classes
+      css_classes = super
+      user_theme = Redmine::Themes.theme(User.current.pref.others[:ui_theme])
       user_theme ?
-          css_classes.gsub(/theme-\S+/, "theme-#{user_theme.name}") :
-          css_classes
+        css_classes.gsub(/theme-\S+/, "theme-#{user_theme.name}") :
+        css_classes
     end
 
   end
diff --git a/lib/redmine_user_specific_theme/patches/user_preference_patch.rb b/lib/redmine_user_specific_theme/patches/user_preference_patch.rb
index 6c2cd1c..4cec186 100644
--- a/lib/redmine_user_specific_theme/patches/user_preference_patch.rb
+++ b/lib/redmine_user_specific_theme/patches/user_preference_patch.rb
@@ -1,27 +1,17 @@
-require_dependency 'user_preference'
+require_dependency 'my_controller'
 
 module RedmineUserSpecificTheme
   module Patches
     module UserPreferencePatch
-
-      def self.prepended(base)
-        base.class_eval do
-          if defined? safe_attributes
-            safe_attributes :ui_theme
-          end
+      def account
+        Rails.logger.info "Account with theme patch applied"
+        if request.put? && params[:pref]
+          theme = params[:pref][:ui_theme]
+          User.current.pref.others[:ui_theme] = theme if theme
+          User.current.pref.save
+          Rails.logger.info "Saved theme: #{theme}"
         end
-      end
-
-      def ui_theme
-        self[:ui_theme]
-      end
-
-      def ui_theme=(val)
-        self[:ui_theme] = val
-      end
-
-      def ui_theme?
-        ui_theme.blank?
+        super
       end
 
     end