diff --git a/Gemfile b/Gemfile
old mode 100644
new mode 100755
diff --git a/Guardfile b/Guardfile
old mode 100644
new mode 100755
index ee91a50..b0f555b
--- a/Guardfile
+++ b/Guardfile
@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 # A sample Guardfile
 # More info at https://github.com/guard/guard#readme
 
-guard :rspec, cmd: "bundle exec rspec" do
+guard :rspec, cmd: 'bundle exec rspec' do
   watch(%r{^spec/.+_spec\.rb$})
   watch(%r{^lib/(.+)\.rb$})     { |m| "spec/lib/#{m[1]}_spec.rb" }
-  watch('spec/spec_helper.rb')  { "spec" }
+  watch('spec/spec_helper.rb')  { 'spec' }
 end
diff --git a/LICENSE.txt b/LICENSE.txt
old mode 100644
new mode 100755
diff --git a/README.md b/README.md
old mode 100644
new mode 100755
diff --git a/Rakefile b/Rakefile
old mode 100644
new mode 100755
index 2995527..c702cfc
--- a/Rakefile
+++ b/Rakefile
@@ -1 +1 @@
-require "bundler/gem_tasks"
+require 'bundler/gem_tasks'
diff --git a/lib/mongoid/enum.rb b/lib/mongoid/enum.rb
old mode 100644
new mode 100755
index 20dc37e..f065606
--- a/lib/mongoid/enum.rb
+++ b/lib/mongoid/enum.rb
@@ -1,12 +1,13 @@
-require "mongoid/enum/version"
-require "mongoid/enum/validators/multiple_validator"
-require "mongoid/enum/configuration"
+# frozen_string_literal: true
+
+require 'mongoid/enum/version'
+require 'mongoid/enum/validators/multiple_validator'
+require 'mongoid/enum/configuration'
 
 module Mongoid
   module Enum
     extend ActiveSupport::Concern
     module ClassMethods
-
       def enum(name, values, options = {})
         field_name = :"#{Mongoid::Enum.configuration.field_name_prefix}#{name}"
         options = default_options(values).merge(options)
@@ -21,12 +22,13 @@ def enum(name, values, options = {})
       end
 
       private
+
       def default_options(values)
         {
-          :multiple => false,
-          :default  => values.first,
-          :required => true,
-          :validate => true
+          multiple: false,
+          default: values.first,
+          required: true,
+          validate: true
         }
       end
 
@@ -37,21 +39,21 @@ def set_values_constant(name, values)
 
       def create_field(field_name, options)
         type = options[:multiple] && Array || Symbol
-        field field_name, :type => type, :default => options[:default]
+        field field_name, type: type, default: options[:default]
       end
 
       def create_validations(field_name, values, options)
         if options[:multiple] && options[:validate]
-          validates field_name, :'mongoid/enum/validators/multiple' => { :in => values.map(&:to_sym), :allow_nil => !options[:required] }
-        #FIXME: Shouldn't this be `elsif options[:validate]` ???
+          validates field_name, 'mongoid/enum/validators/multiple': { in: values.map(&:to_sym), allow_nil: !options[:required] }
+        # FIXME: Shouldn't this be `elsif options[:validate]` ???
         elsif validate
-          validates field_name, :inclusion => {:in => values.map(&:to_sym)}, :allow_nil => !options[:required]
+          validates field_name, inclusion: { in: values.map(&:to_sym) }, allow_nil: !options[:required]
         end
       end
 
       def define_value_scopes_and_accessors(field_name, values, options)
         values.each do |value|
-          scope value, ->{ where(field_name => value) }
+          scope value, -> { where(field_name => value) }
 
           if options[:multiple]
             define_array_accessor(field_name, value)
diff --git a/lib/mongoid/enum/configuration.rb b/lib/mongoid/enum/configuration.rb
old mode 100644
new mode 100755
index ed45df4..8879898
--- a/lib/mongoid/enum/configuration.rb
+++ b/lib/mongoid/enum/configuration.rb
@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 module Mongoid
   module Enum
     class Configuration
       attr_accessor :field_name_prefix
 
       def initialize
-        self.field_name_prefix = "_"
+        self.field_name_prefix = '_'
       end
     end
 
diff --git a/lib/mongoid/enum/validators/multiple_validator.rb b/lib/mongoid/enum/validators/multiple_validator.rb
old mode 100644
new mode 100755
index 3360816..1e7f5e2
--- a/lib/mongoid/enum/validators/multiple_validator.rb
+++ b/lib/mongoid/enum/validators/multiple_validator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Mongoid
   module Enum
     module Validators
@@ -6,14 +8,14 @@ def validate_each(record, attribute, values)
           values = Array(values)
 
           if options[:allow_nil]
-            add_error_message record, attribute if !all_included?(values, options[:in])
+            add_error_message record, attribute unless all_included?(values, options[:in])
           else
             add_error_message record, attribute if values.empty? || !all_included?(values, options[:in])
           end
         end
 
         def add_error_message(record, attribute)
-          record.errors[attribute] << (options[:message] || "is not in #{options[:in].join ", "}")
+          record.errors[attribute] << (options[:message] || "is not in #{options[:in].join ', '}")
         end
 
         def all_included?(values, allowed)
diff --git a/lib/mongoid/enum/version.rb b/lib/mongoid/enum/version.rb
old mode 100644
new mode 100755
index 0067529..6f672e9
--- a/lib/mongoid/enum/version.rb
+++ b/lib/mongoid/enum/version.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 module Mongoid
   module Enum
-    VERSION = "0.4.0"
+    VERSION = '0.4.0'
   end
 end
diff --git a/mongoid-enum.gemspec b/mongoid-enum.gemspec
old mode 100644
new mode 100755
index bd9465d..a3f962d
--- a/mongoid-enum.gemspec
+++ b/mongoid-enum.gemspec
@@ -1,28 +1,29 @@
-# coding: utf-8
-lib = File.expand_path('../lib', __FILE__)
+# frozen_string_literal: true
+
+lib = File.expand_path('lib', __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'mongoid/enum/version'
 
 Gem::Specification.new do |spec|
-  spec.name          = "mongoid-enum"
+  spec.name          = 'mongoid-enum'
   spec.version       = Mongoid::Enum::VERSION
-  spec.authors       = ["Nicholas Bruning"]
-  spec.email         = ["nicholas@bruning.com.au"]
-  spec.description   = %q{Heavily inspired by DDH's ActiveRecord::Enum, this little library is there to help you cut down the cruft in your models and make the world a happier place at the same time.}
-  spec.summary       = %q{Sweet enum sugar for your Mongoid documents}
-  spec.homepage      = "https://github.com/thetron/mongoid-enum"
-  spec.license       = "MIT"
+  spec.authors       = ['Nicholas Bruning']
+  spec.email         = ['nicholas@bruning.com.au']
+  spec.description   = "Heavily inspired by DDH's ActiveRecord::Enum, this little library is there to help you cut down the cruft in your models and make the world a happier place at the same time."
+  spec.summary       = 'Sweet enum sugar for your Mongoid documents'
+  spec.homepage      = 'https://github.com/thetron/mongoid-enum'
+  spec.license       = 'MIT'
 
-  spec.files         = `git ls-files`.split($/)
+  spec.files         = `git ls-files`.split($INPUT_RECORD_SEPARATOR)
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
-  spec.require_paths = ["lib"]
+  spec.require_paths = ['lib']
 
-  spec.add_runtime_dependency "mongoid", "~> 5.0"
+  spec.add_runtime_dependency 'mongoid', '>= 5.0'
 
-  spec.add_development_dependency "bundler", "~> 1.3"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "rspec", "~> 3.1"
-  spec.add_development_dependency "guard-rspec", "~> 4.6.2"
-  spec.add_development_dependency "mongoid-rspec", "~> 3.0"
+  spec.add_development_dependency 'bundler', '~> 1.3'
+  spec.add_development_dependency 'rake'
+  spec.add_development_dependency 'rspec', '~> 3.1'
+  spec.add_development_dependency 'guard-rspec', '~> 4.6.2'
+  spec.add_development_dependency 'mongoid-rspec', '~> 3.0'
 end
diff --git a/spec/mongoid/configuration_spec.rb b/spec/mongoid/configuration_spec.rb
old mode 100644
new mode 100755
index db04d68..f903fa6
--- a/spec/mongoid/configuration_spec.rb
+++ b/spec/mongoid/configuration_spec.rb
@@ -1,11 +1,13 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Mongoid::Enum::Configuration do
   subject { Mongoid::Enum::Configuration.new }
 
-  describe "field_name_prefix" do
+  describe 'field_name_prefix' do
     it "has '_' as default value" do
-      expect(subject.field_name_prefix).to eq "_"
+      expect(subject.field_name_prefix).to eq '_'
     end
   end
 end
diff --git a/spec/mongoid/enum/validators/multiple_validator_spec.rb b/spec/mongoid/enum/validators/multiple_validator_spec.rb
old mode 100644
new mode 100755
index d47c605..613a7a4
--- a/spec/mongoid/enum/validators/multiple_validator_spec.rb
+++ b/spec/mongoid/enum/validators/multiple_validator_spec.rb
@@ -1,59 +1,61 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 require 'ostruct'
 
 describe Mongoid::Enum::Validators::MultipleValidator do
   subject { Mongoid::Enum::Validators::MultipleValidator }
-  let(:values) { [:lorem, :ipsum, :dolor, :sit] }
+  let(:values) { %i[lorem ipsum dolor sit] }
   let(:attribute) { :word }
-  let(:record) { OpenStruct.new(:errors => {attribute => []}, attribute => values.first) }
+  let(:record) { OpenStruct.new(:errors => { attribute => [] }, attribute => values.first) }
   let(:allow_nil) { false }
-  let(:validator) { subject.new(:attributes => attribute, :in => values, :allow_nil => allow_nil) }
+  let(:validator) { subject.new(attributes: attribute, in: values, allow_nil: allow_nil) }
 
-  describe ".validate_each" do
-    context "when allow_nil: true" do
+  describe '.validate_each' do
+    context 'when allow_nil: true' do
       let(:allow_nil) { true }
 
-      context "and value is nil" do
+      context 'and value is nil' do
         before(:each) { validator.validate_each(record, attribute, nil) }
-        it "validates" do
+        it 'validates' do
           expect(record.errors[attribute].empty?).to be true
         end
       end
 
-      context "and value is []" do
+      context 'and value is []' do
         before(:each) { validator.validate_each(record, attribute, []) }
-        it "validates" do
+        it 'validates' do
           expect(record.errors[attribute].empty?).to be true
         end
       end
     end
 
-    context "when allow_nil: false" do
-      context "and value is nil" do
+    context 'when allow_nil: false' do
+      context 'and value is nil' do
         before(:each) { validator.validate_each(record, attribute, nil) }
         it "won't validate" do
           expect(record.errors[attribute].any?).to be true
-          expect(record.errors[attribute]).to eq ["is not in #{values.join ", "}"]
+          expect(record.errors[attribute]).to eq ["is not in #{values.join ', '}"]
         end
       end
-      context "and value is []" do
+      context 'and value is []' do
         before(:each) { validator.validate_each(record, attribute, []) }
         it "won't validate" do
           expect(record.errors[attribute].any?).to be true
-          expect(record.errors[attribute]).to eq ["is not in #{values.join ", "}"]
+          expect(record.errors[attribute]).to eq ["is not in #{values.join ', '}"]
         end
       end
     end
 
-    context "when value is included" do
+    context 'when value is included' do
       let(:allow_nil) { rand(2).zero? }
       before(:each) { validator.validate_each(record, attribute, [values.sample]) }
-      it "validates" do
+      it 'validates' do
         expect(record.errors[attribute].empty?).to be true
       end
     end
 
-    context "when value is not included" do
+    context 'when value is not included' do
       let(:allow_nil) { rand(2).zero? }
       before(:each) { validator.validate_each(record, attribute, [:amet]) }
       it "won't validate" do
@@ -61,15 +63,15 @@
       end
     end
 
-    context "when multiple values included" do
+    context 'when multiple values included' do
       let(:allow_nil) { rand(2).zero? }
       before(:each) { validator.validate_each(record, attribute, [values.first, values.last]) }
-      it "validates" do
+      it 'validates' do
         expect(record.errors[attribute].empty?).to be true
       end
     end
 
-    context "when one value is not included "do
+    context 'when one value is not included ' do
       let(:allow_nil) { rand(2).zero? }
       before(:each) { validator.validate_each(record, attribute, [values.first, values.last, :amet]) }
       it "won't validate" do
diff --git a/spec/mongoid/enum_spec.rb b/spec/mongoid/enum_spec.rb
old mode 100644
new mode 100755
index 5bd9c3c..6003e42
--- a/spec/mongoid/enum_spec.rb
+++ b/spec/mongoid/enum_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 require 'mongoid/enum/configuration'
 
@@ -5,8 +7,8 @@ class User
   include Mongoid::Document
   include Mongoid::Enum
 
-  enum :status, [:awaiting_approval, :approved, :banned]
-  enum :roles, [:author, :editor, :admin], :multiple => true, :default => [], :required => false
+  enum :status, %i[awaiting_approval approved banned]
+  enum :roles, %i[author editor admin], multiple: true, default: [], required: false
 end
 
 describe Mongoid::Enum do
@@ -14,54 +16,54 @@ class User
   let(:instance) { User.new }
   let(:alias_name) { :status }
   let(:field_name) { :"_#{alias_name}" }
-  let(:values) { [:awaiting_approval, :approved, :banned] }
-  let(:multiple_field_name) { :"_roles" }
+  let(:values) { %i[awaiting_approval approved banned] }
+  let(:multiple_field_name) { :_roles }
 
-  describe "field" do
-    it "is defined" do
+  describe 'field' do
+    it 'is defined' do
       expect(klass).to have_field(field_name)
     end
 
-    it "uses prefix defined in configuration" do
+    it 'uses prefix defined in configuration' do
       old_field_name_prefix = Mongoid::Enum.configuration.field_name_prefix
       Mongoid::Enum.configure do |config|
-        config.field_name_prefix = "___"
+        config.field_name_prefix = '___'
       end
       UserWithoutPrefix = Class.new do
         include Mongoid::Document
         include Mongoid::Enum
 
-        enum :status, [:awaiting_approval, :approved, :banned]
+        enum :status, %i[awaiting_approvalapproved banned]
       end
-      expect(UserWithoutPrefix).to have_field "___status"
+      expect(UserWithoutPrefix).to have_field '___status'
       Mongoid::Enum.configure do |config|
         config.field_name_prefix = old_field_name_prefix
       end
     end
 
-    it "is aliased" do
+    it 'is aliased' do
       expect(instance).to respond_to alias_name
       expect(instance).to respond_to :"#{alias_name}="
       expect(instance).to respond_to :"#{alias_name}"
     end
 
-    describe "type" do
-      context "when multiple" do
-        it "is an array" do
+    describe 'type' do
+      context 'when multiple' do
+        it 'is an array' do
           expect(klass).to have_field(multiple_field_name).of_type(Array)
         end
 
-        it "validates using a custom validator" do
+        it 'validates using a custom validator' do
           expect(klass).to custom_validate(multiple_field_name).with_validator(Mongoid::Enum::Validators::MultipleValidator)
         end
       end
 
-      context "when not multiple" do
-        it "is a symbol" do
+      context 'when not multiple' do
+        it 'is a symbol' do
           expect(klass).to have_field(field_name).of_type(Symbol)
         end
 
-        it "validates inclusion in values" do
+        it 'validates inclusion in values' do
           expect(klass).to validate_inclusion_of(field_name).to_allow(values)
         end
       end
@@ -69,59 +71,59 @@ class User
   end
 
   describe "'required' option" do
-    context "when true" do
+    context 'when true' do
       let(:instance) { User.new status: nil }
-      it "is not valid with nil value" do
+      it 'is not valid with nil value' do
         expect(instance).to_not be_valid
       end
     end
 
-    context "when false" do
+    context 'when false' do
       let(:instance) { User.new roles: nil }
-      it "is valid with nil value" do
+      it 'is valid with nil value' do
         expect(instance).to be_valid
       end
     end
   end
 
-  describe "constant" do
-    it "is set to the values" do
+  describe 'constant' do
+    it 'is set to the values' do
       expect(klass::STATUS).to eq values
     end
   end
 
-  describe "accessors" do
-    context "when singular" do
-      describe "setter" do
-        it "accepts strings" do
+  describe 'accessors' do
+    context 'when singular' do
+      describe 'setter' do
+        it 'accepts strings' do
           instance.status = 'banned'
           expect(instance.status).to eq :banned
         end
 
-        it "accepts symbols" do
+        it 'accepts symbols' do
           instance.status = :banned
           expect(instance.status).to eq :banned
         end
       end
 
-      describe "{{value}}!" do
-        it "sets the value" do
+      describe '{{value}}!' do
+        it 'sets the value' do
           instance.save
           instance.banned!
           expect(instance.status).to eq :banned
         end
       end
 
-      describe "{{value}}?" do
-        context "when {{enum}} == {{value}}" do
-          it "returns true" do
+      describe '{{value}}?' do
+        context 'when {{enum}} == {{value}}' do
+          it 'returns true' do
             instance.save
             instance.banned!
             expect(instance.banned?).to eq true
           end
         end
-        context "when {{enum}} != {{value}}" do
-          it "returns false" do
+        context 'when {{enum}} != {{value}}' do
+          it 'returns false' do
             instance.save
             instance.banned!
             expect(instance.approved?).to eq false
@@ -130,19 +132,19 @@ class User
       end
     end
 
-    context "when multiple" do
-      describe "setter" do
-        it "accepts strings" do
-          instance.roles = "author"
+    context 'when multiple' do
+      describe 'setter' do
+        it 'accepts strings' do
+          instance.roles = 'author'
           expect(instance.roles).to eq [:author]
         end
 
-        it "accepts symbols" do
+        it 'accepts symbols' do
           instance.roles = :author
           expect(instance.roles).to eq [:author]
         end
 
-        it "accepts arrays of strings" do
+        it 'accepts arrays of strings' do
           instance.roles = ['author', 'editor']
           instance.save
           puts instance.errors.full_messages
@@ -151,16 +153,16 @@ class User
           expect(instance.roles).to include(:editor)
         end
 
-        it "accepts arrays of symbols"  do
+        it 'accepts arrays of symbols'  do
           instance.roles = [:author, :editor]
           expect(instance.roles).to include(:author)
           expect(instance.roles).to include(:editor)
         end
       end
 
-      describe "{{value}}!" do
-        context "when field is nil" do
-          it "creates an array containing the value" do
+      describe '{{value}}!' do
+        context 'when field is nil' do
+          it 'creates an array containing the value' do
             instance.roles = nil
             instance.save
             instance.author!
@@ -168,19 +170,19 @@ class User
           end
         end
 
-        context "when field is not nil" do
-          it "appends the value" do
+        context 'when field is not nil' do
+          it 'appends the value' do
             instance.save
             instance.author!
             instance.editor!
-            expect(instance.roles).to eq [:author, :editor]
+            expect(instance.roles).to eq %i[author editor]
           end
         end
       end
 
-      describe "{{value}}?" do
-        context "when {{enum}} contains {{value}}" do
-          it "returns true" do
+      describe '{{value}}?' do
+        context 'when {{enum}} contains {{value}}' do
+          it 'returns true' do
             instance.save
             instance.author!
             instance.editor!
@@ -189,8 +191,8 @@ class User
           end
         end
 
-        context "when {{enum}} does not contain {{value}}" do
-          it "returns false" do
+        context 'when {{enum}} does not contain {{value}}' do
+          it 'returns false' do
             instance.save
             expect(instance.author?).to be false
           end
@@ -199,18 +201,18 @@ class User
     end
   end
 
-  describe "scopes" do
-    context "when singular" do
-      it "returns the corresponding documents" do
+  describe 'scopes' do
+    context 'when singular' do
+      it 'returns the corresponding documents' do
         instance.save
         instance.banned!
         expect(User.banned.to_a).to eq [instance]
       end
     end
 
-    context "when multiple" do
-      context "and only one document" do
-        it "returns that document" do
+    context 'when multiple' do
+      context 'and only one document' do
+        it 'returns that document' do
           instance.save
           instance.author!
           instance.editor!
@@ -218,8 +220,8 @@ class User
         end
       end
 
-      context "and more than one document" do
-        it "returns all documents with those values" do
+      context 'and more than one document' do
+        it 'returns all documents with those values' do
           instance.save
           instance.author!
           instance.editor!
@@ -232,36 +234,36 @@ class User
     end
   end
 
-  describe "default values" do
-    context "when not specified" do
-      it "uses the first value" do
+  describe 'default values' do
+    context 'when not specified' do
+      it 'uses the first value' do
         instance.save
         expect(instance.status).to eq values.first
       end
     end
 
-    context "when specified" do
-      it "uses the specified value" do
+    context 'when specified' do
+      it 'uses the specified value' do
         instance.save
         expect(instance.roles).to eq []
       end
     end
   end
 
-  describe ".configuration" do
-    it "returns Configuration object" do
+  describe '.configuration' do
+    it 'returns Configuration object' do
       expect(Mongoid::Enum.configuration)
-          .to be_instance_of Mongoid::Enum::Configuration
+        .to be_instance_of Mongoid::Enum::Configuration
     end
-    it "returns same object when called multiple times" do
+    it 'returns same object when called multiple times' do
       expect(Mongoid::Enum.configuration).to be Mongoid::Enum.configuration
     end
   end
 
-  describe ".configure" do
-    it "yields configuration if block is given" do
+  describe '.configure' do
+    it 'yields configuration if block is given' do
       expect { |b| Mongoid::Enum.configure &b }
-          .to yield_with_args Mongoid::Enum.configuration
+        .to yield_with_args Mongoid::Enum.configuration
     end
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
old mode 100644
new mode 100755
diff --git a/spec/support/mongoid.yml b/spec/support/mongoid.yml
old mode 100644
new mode 100755