diff --git a/Rakefile b/Rakefile
index fbff659..ea2925c 100644
--- a/Rakefile
+++ b/Rakefile
@@ -8,7 +8,7 @@ task test: :spec
 
 # Testing with rspec
 RSpec::Core::RakeTask.new(:spec) do |task|
-  task.rspec_opts = %w(--color --format documentation)
+  task.rspec_opts = %w[--color --format documentation]
 end
 task test: :spec
 
@@ -22,8 +22,8 @@ end
 # Documentation
 desc "Generate gem documentation (same as running 'rake yard')"
 YARD::Rake::YardocTask.new do |t|
-  t.files = %w(lib/**/*.rb)
-  t.stats_options = %w(--list-undoc --compact)
+  t.files = %w[lib/**/*.rb]
+  t.stats_options = %w[--list-undoc --compact]
 end
 task doc: :yard
 
diff --git a/faker_japanese.gemspec b/faker_japanese.gemspec
index a51f131..f5eb052 100644
--- a/faker_japanese.gemspec
+++ b/faker_japanese.gemspec
@@ -26,7 +26,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rspec-expectations', '~> 3.2.0'
   spec.add_development_dependency 'rspec-mocks', '~> 3.2.1'
   spec.add_development_dependency 'awesome_print', '~> 1.6.1'
-  spec.add_development_dependency 'looksee', '~> 3.1.0'
+  spec.add_development_dependency 'looksee', '~> 4.0.0'
   spec.add_development_dependency 'pry', '~> 0.10.1'
   spec.add_development_dependency 'yard', '~> 0.8.7.6'
   spec.add_development_dependency 'fuubar'
diff --git a/lib/faker_japanese.rb b/lib/faker_japanese.rb
index f1efd7a..3f3e451 100644
--- a/lib/faker_japanese.rb
+++ b/lib/faker_japanese.rb
@@ -1,12 +1,13 @@
 require 'faker'
 require 'yaml'
+require 'pathname'
 
 # Faker
 module Faker
   # Japanese localization for Faker
   module Japanese
-    # Location on the disk of this script
-    SELFDIR = File.expand_path(File.dirname(__FILE__))
+    # Working directory where this script is located
+    WORKDIR = Pathname.new(::File.expand_path(::File.dirname(__FILE__)))
 
     # Kanji string
     class Kanji < String
@@ -33,14 +34,14 @@ def initialize(kanji, yomi, kana, romaji)
     # Faker Base class
     class Base
       class << self
-        # Using callback to store loaded data when subclass is created
+        # Use callback to store loaded data when subclass is created
         # @param [Class] klass class name
         def inherited(klass)
           fail("#{klass} should be Class") unless klass.is_a? Class
           klass.class_variable_set '@@data', load_data(klass)
         end
 
-        # Convert full class name to lower case string with class name only
+        # Convert full class name to the lower case string with class name only
         # @param [Class] klass class name
         # @return [String]
         def demodulize(klass)
@@ -51,7 +52,7 @@ def demodulize(klass)
         # @param [String] filepath full path to the file
         # @return [Hash]
         def load_raw_yaml(filepath)
-          return nil unless filepath && File.readable?(filepath)
+          return nil unless filepath && ::File.readable?(filepath)
           YAML.load_file(filepath).each_with_object({}) do |(k, v), h|
             h[k.to_sym] = v
           end
@@ -60,10 +61,8 @@ def load_raw_yaml(filepath)
         # Created dictionary with loaded data
         # @param [Module] klass class name
         def load_data(klass)
-          datafile = File.join(SELFDIR,
-                               'faker_japanese',
-                               'data', "#{demodulize(klass)}.yml")
-          data = load_raw_yaml(datafile)
+          datafile = "#{demodulize(klass)}.yml"
+          data = load_raw_yaml(WORKDIR.join('faker_japanese', 'data', datafile))
           return data if data.nil?
           data.inject({}) do |res, item|
             key, values = item
@@ -72,7 +71,7 @@ def load_data(klass)
           data
         end
 
-        # Fetch random value from name dictionary
+        # Fetch random value from the name dictionary
         # @param [String] key in the @@data
         # @return [Kanji]
         def fetch(key)
@@ -80,7 +79,7 @@ def fetch(key)
           val[rand(val.size)]
         end
 
-        # Swap method if block was evaluated to true
+        # Swap methods if block was evaluated to true
         # @param [Class] klass name of the class
         # @param [Symbol] name method name
         def swap_method(klass, name)
@@ -94,9 +93,7 @@ def swap_method(klass, name)
         # @param [Class] klass name of the class
         # @param [Symbol] name method name
         def use_japanese_method(klass, name)
-          swap_method(klass, name) do
-            Faker::Config.locale == :ja
-          end
+          swap_method(klass, name) { Faker::Config.locale == :ja }
         end
       end # << self
     end # Base
diff --git a/lib/faker_japanese/version.rb b/lib/faker_japanese/version.rb
index e287c13..d090c93 100644
--- a/lib/faker_japanese/version.rb
+++ b/lib/faker_japanese/version.rb
@@ -2,6 +2,6 @@ module Faker
   # Japanese localization for Faker
   module Japanese
     # Current version
-    VERSION = '0.2.2'
+    VERSION = '0.2.2'.freeze
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 34cfeac..03a5f4c 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,8 +3,8 @@
 require 'coveralls'
 
 SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
-    Coveralls::SimpleCov::Formatter,
-    SimpleCov::Formatter::HTMLFormatter
+  Coveralls::SimpleCov::Formatter,
+  SimpleCov::Formatter::HTMLFormatter
 ]
 SimpleCov.start do
   # disable coverage tracking
@@ -22,7 +22,7 @@
 class String
   # Method to check if string contains cjk characters
   def contains_cjk?
-    !!(self =~ /\p{Han}|\p{Katakana}|\p{Hiragana}|\p{Hangul}/)
+    (self =~ /\p{Han}|\p{Katakana}|\p{Hiragana}|\p{Hangul}/)
   end
 end