diff --git a/.rubocop.yml b/.rubocop.yml
index 73f287e..2e62f76 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -2,6 +2,7 @@
 AllCops:
   TargetRubyVersion: 2.3
   Exclude:
+    - "bin/**/*"
     - "spec/dummy/bin/**/*"
     - "tmp/**/*"
     - "vendor/**/*"
diff --git a/letter_opener_web.gemspec b/letter_opener_web.gemspec
index 79762f7..7b7aced 100644
--- a/letter_opener_web.gemspec
+++ b/letter_opener_web.gemspec
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-lib = File.expand_path('../lib', __FILE__)
+lib = File.expand_path('lib', __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'letter_opener_web/version'
 
diff --git a/spec/models/letter_opener_web/letter_spec.rb b/spec/models/letter_opener_web/letter_spec.rb
index 0ef43cb..84aaf1f 100644
--- a/spec/models/letter_opener_web/letter_spec.rb
+++ b/spec/models/letter_opener_web/letter_spec.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 describe LetterOpenerWeb::Letter do
-  let(:location) { File.expand_path('../../../tmp', __FILE__) }
+  let(:location) { File.expand_path('../../tmp', __dir__) }
 
   def rich_text(mail_id)
     <<-MAIL
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index 94a80d1..3f6d2a6 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 ENV['RAILS_ENV'] ||= 'test'
-require File.expand_path('../dummy/config/environment', __FILE__)
+require File.expand_path('dummy/config/environment', __dir__)
 require 'spec_helper'
 require 'rspec/rails'