diff --git a/.rubocop.yml b/.rubocop.yml
index 745e154..932c41e 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -35,3 +35,9 @@ Style/StructInheritance:
 
 Metrics/ModuleLength:
   Enabled: false
+
+Metrics/BlockLength:
+  Enabled: false
+
+Security/YAMLLoad:
+  Enabled: false
diff --git a/.ruby-version b/.ruby-version
index 94b04ed..005119b 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-ruby-2.2.2
+2.4.1
diff --git a/.travis.yml b/.travis.yml
index 11e48a2..3844f2d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,10 +3,10 @@ services:
 - redis-server
 language: ruby
 rvm:
-- 2.2.0
-- 2.4.1
-- jruby-1.7.18
-- rbx-2.5.0
+- 2.2.4
+- 2.3.0
+- 2.4.0
+- jruby-9.1.9.0
 env:
   global:
     secure: LrTz0Pq2ibNZuKDhdzcrvEUSNxUpPopEq9aJeCxy3UpV0v4vpHBtWV0S6zofvf98g/RkZ6cGI1u+0H578dHgE6pWTo+iR8LAwqPKofrFIWRkeo+M77Vs5swahb3mQyPOcig1hfVWDm25MsojePYm70eBIcBU55NWImtdePXfiU0=
diff --git a/Gemfile b/Gemfile
index bd3fa6b..3466afb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,11 +1,13 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 gem 'rake'
 gem 'rspec'
 
 platform :mri do
-  gem 'codeclimate-test-reporter', require: nil
   gem 'cane'
+  gem 'codeclimate-test-reporter', require: nil
   gem 'rubocop', require: false
   gem 'simplecov', require: false
 end
diff --git a/README.md b/README.md
index 707e779..567c0b2 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,10 @@
 
 ActiveModel + Redis with the aim to mimic ActiveRecord where possible.
 
+## Requirements
+
+Modis supports CRuby 2.2.2+ and jRuby 9k+
+
 ## Installation
 
 Add this line to your application's Gemfile:
diff --git a/Rakefile b/Rakefile
index 058c233..d860faa 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "rake"
 require "bundler/gem_tasks"
 require "rspec/core/rake_task"
diff --git a/benchmark/bench.rb b/benchmark/bench.rb
index bbb5fec..523de06 100644
--- a/benchmark/bench.rb
+++ b/benchmark/bench.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'stackprof'
 require 'benchmark'
 
@@ -40,14 +42,14 @@ def _run
 
   private
 
-  def with_profile(name, &blk)
+  def with_profile(name)
     if ENV['PROFILE']
       mode = :wall
       out = "tmp/stackprof-#{mode}-#{name}.dump"
       @profiles << out
-      StackProf.run(mode: mode, out: out, &blk)
+      StackProf.run(mode: mode, out: out, &Proc.new)
     else
-      blk.call
+      yield
     end
   end
 
diff --git a/benchmark/find.rb b/benchmark/find.rb
index 97d6cf8..57193e9 100755
--- a/benchmark/find.rb
+++ b/benchmark/find.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift('benchmark')
 require 'bench'
 
@@ -16,7 +18,7 @@ class User
   attribute :flag, :boolean
   attribute :array, :array
   attribute :hash, :hash
-  attribute :string_or_hash, [:string, :hash]
+  attribute :string_or_hash, %i[string hash]
 
   index :name
 end
diff --git a/benchmark/persistence.rb b/benchmark/persistence.rb
index f9d88a3..9484af4 100644
--- a/benchmark/persistence.rb
+++ b/benchmark/persistence.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift('benchmark')
 require 'bench'
 
@@ -16,7 +18,7 @@ class User
   attribute :flag, :boolean
   attribute :array, :array
   attribute :hash, :hash
-  attribute :string_or_hash, [:string, :hash]
+  attribute :string_or_hash, %i[string hash]
 
   index :name
 end
diff --git a/lib/modis.rb b/lib/modis.rb
index f7f750e..50a0660 100644
--- a/lib/modis.rb
+++ b/lib/modis.rb
@@ -1,8 +1,9 @@
+# frozen_string_literal: true
+
 require 'redis'
 require 'connection_pool'
 require 'active_model'
 require 'active_support/all'
-require 'yaml'
 require 'msgpack'
 
 require 'modis/version'
diff --git a/lib/modis/attribute.rb b/lib/modis/attribute.rb
index bd2025e..98e8aed 100644
--- a/lib/modis/attribute.rb
+++ b/lib/modis/attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   module Attribute
     TYPES = { string: [String],
diff --git a/lib/modis/configuration.rb b/lib/modis/configuration.rb
index 170abd7..c7933c7 100644
--- a/lib/modis/configuration.rb
+++ b/lib/modis/configuration.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   def self.configure
     yield config
diff --git a/lib/modis/errors.rb b/lib/modis/errors.rb
index 6937466..c3d82a2 100644
--- a/lib/modis/errors.rb
+++ b/lib/modis/errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   class ModisError < StandardError; end
   class RecordNotSaved < ModisError; end
diff --git a/lib/modis/finder.rb b/lib/modis/finder.rb
index dead104..48068a2 100644
--- a/lib/modis/finder.rb
+++ b/lib/modis/finder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   module Finder
     def self.included(base)
@@ -61,7 +63,7 @@ def records_to_models(records)
 
       def model_for(attributes)
         cls = model_class(attributes)
-        return unless self == cls || cls < self
+        return unless cls == self || cls < self
         cls.new(attributes, new_record: false)
       end
 
diff --git a/lib/modis/index.rb b/lib/modis/index.rb
index 0af55f9..c397056 100644
--- a/lib/modis/index.rb
+++ b/lib/modis/index.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   module Index
     def self.included(base)
diff --git a/lib/modis/model.rb b/lib/modis/model.rb
index d46c448..790bf76 100644
--- a/lib/modis/model.rb
+++ b/lib/modis/model.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   module Model
     def self.included(base)
@@ -42,6 +44,6 @@ def initialize(record = nil, options = {})
     def ==(other)
       super || other.instance_of?(self.class) && id.present? && other.id == id
     end
-    alias_method :eql?, :==
+    alias eql? ==
   end
 end
diff --git a/lib/modis/persistence.rb b/lib/modis/persistence.rb
index f39071e..52b6086 100644
--- a/lib/modis/persistence.rb
+++ b/lib/modis/persistence.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   module Persistence
     def self.included(base)
@@ -5,7 +7,7 @@ def self.included(base)
       base.instance_eval do
         class << self
           attr_reader :sti_child
-          alias_method :sti_child?, :sti_child
+          alias sti_child? sti_child
         end
       end
     end
@@ -71,7 +73,6 @@ def create!(attrs)
         model
       end
 
-      YAML_MARKER = '---'.freeze
       def deserialize(record)
         values = record.values
         values = MessagePack.unpack(msgpack_array_header(values.size) + values.join)
@@ -79,20 +80,8 @@ def deserialize(record)
         values.each_with_index { |v, i| record[keys[i]] = v }
         record
       rescue MessagePack::MalformedFormatError
-        found_yaml = false
-
         record.each do |k, v|
-          if v.start_with?(YAML_MARKER)
-            found_yaml = true
-            record[k] = YAML.load(v)
-          else
-            record[k] = MessagePack.unpack(v)
-          end
-        end
-
-        if found_yaml
-          id = record['id']
-          STDERR.puts "#{self}(id: #{id}) contains attributes serialized as YAML. As of Modis 1.4.0, YAML is no longer used as the serialization format. To improve performance loading this record, you can force the record to new serialization format (MessagePack) with: #{self}.find(#{id}).save!(yaml_sucks: true)"
+          record[k] = MessagePack.unpack(v)
         end
 
         record
@@ -177,7 +166,7 @@ def coerce_for_persistence(value)
 
     def create_or_update(args = {})
       validate(args)
-      future = persist(args[:yaml_sucks])
+      future = persist
 
       if future && (future == :unchanged || future.value == 'OK')
         reset_changes
@@ -194,7 +183,8 @@ def validate(args)
       raise Modis::RecordInvalid, errors.full_messages.join(', ')
     end
 
-    def persist(persist_all)
+    # rubocop:disable Metrics/AbcSize, Metrics/PerceivedComplexity
+    def persist
       future = nil
       set_id if new_record?
       callback = new_record? ? :create : :update
@@ -203,7 +193,7 @@ def persist(persist_all)
         run_callbacks :save do
           run_callbacks callback do
             redis.pipelined do
-              attrs = coerced_attributes(persist_all)
+              attrs = coerced_attributes
               key = self.class.sti_child? ? self.class.sti_base_key_for(id) : self.class.key_for(id)
               future = attrs.any? ? redis.hmset(key, attrs) : :unchanged
 
@@ -222,10 +212,10 @@ def persist(persist_all)
       future
     end
 
-    def coerced_attributes(persist_all)
+    def coerced_attributes
       attrs = []
 
-      if new_record? || persist_all
+      if new_record?
         attributes.each do |k, v|
           if (self.class.attributes[k][:default] || nil) != v
             attrs << k << coerce_for_persistence(v)
diff --git a/lib/modis/transaction.rb b/lib/modis/transaction.rb
index 461edfe..f3f3849 100644
--- a/lib/modis/transaction.rb
+++ b/lib/modis/transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   module Transaction
     def self.included(base)
diff --git a/lib/modis/version.rb b/lib/modis/version.rb
index aafb787..ebac909 100644
--- a/lib/modis/version.rb
+++ b/lib/modis/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Modis
   VERSION = '1.4.1'
 end
diff --git a/lib/tasks/quality.rake b/lib/tasks/quality.rake
index af33081..a23c571 100644
--- a/lib/tasks/quality.rake
+++ b/lib/tasks/quality.rake
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 begin
   if ENV['TRAVIS']
     namespace :spec do
@@ -16,7 +18,7 @@ begin
     end
 
     namespace :spec do
-      task cane: %w(spec cane_quality)
+      task cane: %w[spec cane_quality]
     end
   end
 rescue LoadError
@@ -37,5 +39,5 @@ rescue LoadError
 end
 
 namespace :spec do
-  task quality: %w(cane rubocop)
+  task quality: %w[cane rubocop]
 end
diff --git a/modis.gemspec b/modis.gemspec
index 013ba32..78fa09e 100644
--- a/modis.gemspec
+++ b/modis.gemspec
@@ -17,8 +17,8 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.require_paths = ["lib"]
 
-  gem.add_runtime_dependency 'activemodel', '>= 3.0', '< 5.0'
-  gem.add_runtime_dependency 'activesupport', '>= 3.0', '< 5.0'
+  gem.add_runtime_dependency 'activemodel', '>= 3.0'
+  gem.add_runtime_dependency 'activesupport', '>= 3.0'
   gem.add_runtime_dependency 'redis', '>= 3.0'
   gem.add_runtime_dependency 'hiredis', '>= 0.5'
   gem.add_runtime_dependency 'connection_pool', '>= 2'
diff --git a/spec/attribute_spec.rb b/spec/attribute_spec.rb
index abbe775..bebc6c2 100644
--- a/spec/attribute_spec.rb
+++ b/spec/attribute_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 module AttributeSpec
@@ -11,7 +13,7 @@ class MockModel
     attribute :flag, :boolean
     attribute :array, :array
     attribute :hash, :hash
-    attribute :string_or_hash, [:string, :hash]
+    attribute :string_or_hash, %i[string hash]
   end
 end
 
diff --git a/spec/errors_spec.rb b/spec/errors_spec.rb
index c3d67f4..2449598 100644
--- a/spec/errors_spec.rb
+++ b/spec/errors_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 module ErrorsSpec
diff --git a/spec/finder_spec.rb b/spec/finder_spec.rb
index c9e9784..49ad86a 100644
--- a/spec/finder_spec.rb
+++ b/spec/finder_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 module FindersSpec
@@ -142,10 +144,10 @@ class Worker < Producer
 
     it 'inherits attributes from the parent' do
       producer = FindersSpec::Producer.create!(name: 'Kyle', consumed: true)
-      expect(producer.attributes.keys.sort).to eq(%w(age child_default id name parent_default type))
+      expect(producer.attributes.keys.sort).to eq(%w[age child_default id name parent_default type])
 
       worker = FindersSpec::Worker.create!(name: 'Max')
-      expect(worker.attributes.keys.sort).to eq(%w(age child_default id name parent_default type))
+      expect(worker.attributes.keys.sort).to eq(%w[age child_default id name parent_default type])
     end
 
     it 'inherits default attribute values from the parent' do
diff --git a/spec/index_spec.rb b/spec/index_spec.rb
index 08d6003..51d98a0 100644
--- a/spec/index_spec.rb
+++ b/spec/index_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 module IndexSpec
diff --git a/spec/persistence_spec.rb b/spec/persistence_spec.rb
index c193a78..a196c72 100644
--- a/spec/persistence_spec.rb
+++ b/spec/persistence_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 module PersistenceSpec
@@ -294,26 +296,4 @@ def test_before_save
       expect(model.update_attributes(name: nil)).to be false
     end
   end
-
-  describe 'YAML backward compatability' do
-    it 'loads a YAML serialized value' do
-      Modis.with_connection do |redis|
-        model.save!
-        key = model.class.key_for(model.id)
-        record = redis.hgetall(key)
-        record['age'] = YAML.dump(30)
-        redis.hmset(key, *record.to_a)
-        record = redis.hgetall(key)
-
-        expect(record['age']).to eq("--- 30\n...\n")
-
-        model.reload
-        expect(model.age).to eq(30)
-
-        model.save!(yaml_sucks: true)
-        record = redis.hgetall(key)
-        expect(record['age']).to eq("\x1E")
-      end
-    end
-  end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index d50ef65..dc979b3 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 unless ENV['TRAVIS']
   begin
     require './spec/support/simplecov_helper'
diff --git a/spec/support/simplecov_helper.rb b/spec/support/simplecov_helper.rb
index 029427a..c1288c9 100644
--- a/spec/support/simplecov_helper.rb
+++ b/spec/support/simplecov_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'simplecov'
 require './spec/support/simplecov_quality_formatter'
 
@@ -17,7 +19,7 @@ def start_simple_cov(name)
         end
       end
 
-      formatter SimpleCov::Formatter::MultiFormatter[*formatters]
+      formatter SimpleCov::Formatter::MultiFormatter.new(*formatters)
     end
   end
 end
diff --git a/spec/support/simplecov_quality_formatter.rb b/spec/support/simplecov_quality_formatter.rb
index 65bdd1d..97b6ff0 100644
--- a/spec/support/simplecov_quality_formatter.rb
+++ b/spec/support/simplecov_quality_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module SimpleCov
   module Formatter
     class QualityFormatter
diff --git a/spec/transaction_spec.rb b/spec/transaction_spec.rb
index eef78ce..420c24a 100644
--- a/spec/transaction_spec.rb
+++ b/spec/transaction_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 module TransactionSpec
diff --git a/spec/validations_spec.rb b/spec/validations_spec.rb
index 5010ff0..e6dadd5 100644
--- a/spec/validations_spec.rb
+++ b/spec/validations_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe 'validations' do