diff --git a/init.rb b/init.rb
index fe06cb1..a343c91 100644
--- a/init.rb
+++ b/init.rb
@@ -1,12 +1,16 @@
-require_dependency 'redmine_issues_tree/hook_listener'
 
 plugin_name = :redmine_issues_tree
+plugin_root = File.dirname(__FILE__)
+
+if Rails.version < '6.0' || !Rails.autoloaders.zeitwerk_enabled?
+  require_dependency plugin_root + '/lib/redmine_issues_tree/hook_listener'
+end
 
 Redmine::Plugin.register plugin_name do
   name 'Redmine Issues Tree plugin'
   author 'Ivan Zabrovskiy'
   description 'Provides a tree view of the issues list'
-  version RedmineIssuesTree::VERSION
+  version RedmineIssuesTree::Version::VERSION
   url 'https://github.com/Loriowar/redmine_issues_tree'
   author_url 'https://loriowar.com/about'
 
@@ -17,7 +21,7 @@
            }
 end
 
-Rails.configuration.to_prepare do
+def patch_init
   prepend_patches_map =
     {
       ::RedmineIssuesTree::IssuesControllerPatch => ::IssuesController
@@ -35,6 +39,16 @@
   end
 end
 
+if Rails.version > '6.0' && Rails.autoloaders.zeitwerk_enabled?
+  Rails.application.config.after_initialize do
+    patch_init
+  end
+else
+  Rails.configuration.to_prepare do
+    patch_init
+  end
+end
+
 # Assign permissions on a tree_view actions. Permissions is same as for :view_issues.
 # Doesn't work without :find_optional_project filter in controller.
 Redmine::AccessControl.
diff --git a/lib/redmine_issues_tree/issues_controller_patch.rb b/lib/redmine_issues_tree/issues_controller_patch.rb
index d7dc967..c18d794 100644
--- a/lib/redmine_issues_tree/issues_controller_patch.rb
+++ b/lib/redmine_issues_tree/issues_controller_patch.rb
@@ -8,7 +8,7 @@ def index
         if settings[:default_redirect_to_tree_view] == 'true'
           # @note: add additional parameter into all links on issues#index looks not so good as parsing a referer
           # @reason: we must prevent redirect to the tree_view if we do some actions on a plain view
-          if skip_issues_tree_redirect == 'true' || URI(request.referer).path == project_issues_path
+          if skip_issues_tree_redirect == 'true' || (request && request.referer && URI(request.referer).path == project_issues_path)
             super
           else
             redirect_to tree_index_project_issues_trees_path(request.query_parameters)
@@ -20,7 +20,7 @@ def index
         if settings[:default_redirect_to_tree_view_without_project] == 'true'
           # @note: add additional parameter into all links on issues#index looks not so good as parsing a referer
           # @reason: we must prevent redirect to the tree_view if we do some actions on a plain view
-          if skip_issues_tree_redirect == 'true' || URI(request.referer).path == issues_path
+          if skip_issues_tree_redirect == 'true' || (request && request.referer && URI(request.referer).path == issues_path)
             super
           else
             redirect_to tree_index_issues_trees_path(request.query_parameters)
diff --git a/lib/redmine_issues_tree/version.rb b/lib/redmine_issues_tree/version.rb
index 486630f..d5954f9 100644
--- a/lib/redmine_issues_tree/version.rb
+++ b/lib/redmine_issues_tree/version.rb
@@ -1,3 +1,3 @@
-module RedmineIssuesTree
+module RedmineIssuesTree::Version
   VERSION = '0.0.14'
 end