diff --git a/.circleci/config.yml b/.circleci/config.yml
index 5d4145ba7..1e0cecaa8 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -64,7 +64,6 @@ workflows:
           matrix:
             parameters:
               docker-image:
-                - mudge/re2-ci:1.8
                 - ruby:1.9
                 - ruby:2.0
                 - ruby:2.1
diff --git a/.rubocop.yml b/.rubocop.yml
index 0d607d730..28074a966 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,7 +1,7 @@
 inherit_from: .rubocop_todo.yml
 
 AllCops:
-  TargetRubyVersion: 2.2 # closest to required_ruby_version of '>= 1.8.6'
+  TargetRubyVersion: 2.2 # closest to required_ruby_version of '>= 1.9'
 
 # Even the reference in the documentation suggests that you should prefer
 # `alias_method` vs `alias`, so I don't understand why that isn't the default.
diff --git a/Gemfile b/Gemfile
index f0b516ed6..e06663915 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,9 +3,7 @@ source 'https://rubygems.org'
 gemspec
 
 # rubocop:disable Bundler/DuplicatedGem
-if RUBY_VERSION < '1.9.3'
-  gem 'rake', '~> 10.0'
-elsif RUBY_VERSION < '2'
+if RUBY_VERSION < '2'
   gem 'rake', '~> 12.2.1'
 elsif RUBY_VERSION < '2.2'
   gem 'rake', '~> 12.3.3'
diff --git a/Rakefile b/Rakefile
index bbcea3b51..48abe5c24 100644
--- a/Rakefile
+++ b/Rakefile
@@ -18,15 +18,10 @@ task 'test' do
 end
 
 namespace 'test' do # rubocop:disable Metrics/BlockLength
-  unit_tests = FileList['test/unit/**/*_test.rb']
-  all_acceptance_tests = FileList['test/acceptance/*_test.rb']
-  ruby186_incompatible_acceptance_tests = FileList['test/acceptance/stub_class_method_defined_on_*_test.rb'] + FileList['test/acceptance/stub_instance_method_defined_on_*_test.rb']
-  ruby186_compatible_acceptance_tests = all_acceptance_tests - ruby186_incompatible_acceptance_tests
-
   desc 'Run unit tests'
   Rake::TestTask.new('units') do |t|
     t.libs << 'test'
-    t.test_files = unit_tests
+    t.test_files = FileList['test/unit/**/*_test.rb']
     t.verbose = true
     t.warning = true
   end
@@ -34,11 +29,7 @@ namespace 'test' do # rubocop:disable Metrics/BlockLength
   desc 'Run acceptance tests'
   Rake::TestTask.new('acceptance') do |t|
     t.libs << 'test'
-    t.test_files = if defined?(RUBY_VERSION) && (RUBY_VERSION >= '1.8.7')
-                     all_acceptance_tests
-                   else
-                     ruby186_compatible_acceptance_tests
-                   end
+    t.test_files = FileList['test/acceptance/*_test.rb']
     t.verbose = true
     t.warning = true
   end
diff --git a/gemfiles/Gemfile.test-unit.latest b/gemfiles/Gemfile.test-unit.latest
index 5600f62e7..265ea8895 100644
--- a/gemfiles/Gemfile.test-unit.latest
+++ b/gemfiles/Gemfile.test-unit.latest
@@ -4,9 +4,5 @@ gemspec :path=>"../"
 
 group :development do
   gem "rake"
-  if RUBY_VERSION < '1.9'
-    gem "test-unit", "~> 2"
-  else
-    gem "test-unit"
-  end
+  gem "test-unit"
 end
diff --git a/lib/mocha.rb b/lib/mocha.rb
index 06546e74f..0b6ab2dc1 100644
--- a/lib/mocha.rb
+++ b/lib/mocha.rb
@@ -1,9 +1 @@
 require 'mocha/version'
-require 'mocha/ruby_version'
-require 'mocha/deprecation'
-
-if Mocha::PRE_RUBY_V19
-  Mocha::Deprecation.warning(
-    'Versions of Ruby earlier than v1.9 will not be supported in future versions of Mocha.'
-  )
-end
diff --git a/lib/mocha/any_instance_method.rb b/lib/mocha/any_instance_method.rb
index 8b128ea99..a821200a1 100644
--- a/lib/mocha/any_instance_method.rb
+++ b/lib/mocha/any_instance_method.rb
@@ -1,4 +1,3 @@
-require 'mocha/ruby_version'
 require 'mocha/stubbed_method'
 
 module Mocha
diff --git a/lib/mocha/instance_method.rb b/lib/mocha/instance_method.rb
index 86909ebe1..37c7f0501 100644
--- a/lib/mocha/instance_method.rb
+++ b/lib/mocha/instance_method.rb
@@ -9,7 +9,7 @@ def mock_owner
     end
 
     def method_body(method)
-      PRE_RUBY_V19 ? proc { |*args, &block| method.call(*args, &block) } : method
+      method
     end
 
     def stubbee_method(method_name)
diff --git a/lib/mocha/integration/test_unit.rb b/lib/mocha/integration/test_unit.rb
index a3fc846e4..cd7791eb7 100644
--- a/lib/mocha/integration/test_unit.rb
+++ b/lib/mocha/integration/test_unit.rb
@@ -3,7 +3,6 @@
 require 'mocha/detection/test_unit'
 
 require 'mocha/integration/test_unit/nothing'
-require 'mocha/integration/test_unit/ruby_version_185_and_below'
 require 'mocha/integration/test_unit/ruby_version_186_and_above'
 require 'mocha/integration/test_unit/gem_version_200'
 require 'mocha/integration/test_unit/gem_version_201_to_202'
@@ -31,7 +30,6 @@ def self.activate
           TestUnit::GemVersion201To202,
           TestUnit::GemVersion200,
           TestUnit::RubyVersion186AndAbove,
-          TestUnit::RubyVersion185AndBelow,
           TestUnit::Nothing
         ].detect { |m| m.applicable_to?(test_unit_version, ruby_version) }
 
diff --git a/lib/mocha/integration/test_unit/ruby_version_185_and_below.rb b/lib/mocha/integration/test_unit/ruby_version_185_and_below.rb
deleted file mode 100644
index cd2a1241d..000000000
--- a/lib/mocha/integration/test_unit/ruby_version_185_and_below.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-require 'mocha/integration/assertion_counter'
-require 'mocha/integration/monkey_patcher'
-require 'mocha/expectation_error'
-
-module Mocha
-  module Integration
-    module TestUnit
-      module RubyVersion185AndBelow
-        def self.applicable_to?(test_unit_version, ruby_version)
-          Gem::Requirement.new('<= 1.2.3').satisfied_by?(test_unit_version) && Gem::Requirement.new('<= 1.8.5').satisfied_by?(ruby_version)
-        end
-
-        def self.description
-          'monkey patch for standard library in Ruby <= v1.8.5'
-        end
-
-        def self.included(mod)
-          MonkeyPatcher.apply(mod, RunMethodPatch)
-        end
-
-        module RunMethodPatch
-          # rubocop:disable all
-          def run(result)
-            assertion_counter = AssertionCounter.new(self)
-            yield(Test::Unit::TestCase::STARTED, name)
-            @_result = result
-            begin
-              begin
-                mocha_setup
-                setup
-                __send__(@method_name)
-                mocha_verify(assertion_counter)
-              rescue Mocha::ExpectationError => e
-                add_failure(e.message, e.backtrace)
-              rescue Test::Unit::AssertionFailedError => e
-                add_failure(e.message, e.backtrace)
-              rescue StandardError, ScriptError
-                add_error($!)
-              ensure
-                begin
-                  teardown
-                rescue Mocha::ExpectationError => e
-                  add_failure(e.message, e.backtrace)
-                rescue Test::Unit::AssertionFailedError => e
-                  add_failure(e.message, e.backtrace)
-                rescue StandardError, ScriptError
-                  add_error($!)
-                end
-              end
-            ensure
-              mocha_teardown
-            end
-            result.add_run
-            yield(Test::Unit::TestCase::FINISHED, name)
-          end
-          # rubocop:enable all
-        end
-      end
-    end
-  end
-end
diff --git a/lib/mocha/mock.rb b/lib/mocha/mock.rb
index e5d96ca27..ea9f05e18 100644
--- a/lib/mocha/mock.rb
+++ b/lib/mocha/mock.rb
@@ -1,4 +1,3 @@
-require 'mocha/singleton_class'
 require 'mocha/expectation'
 require 'mocha/expectation_list'
 require 'mocha/invocation'
@@ -8,7 +7,6 @@
 require 'mocha/parameters_matcher'
 require 'mocha/argument_iterator'
 require 'mocha/expectation_error_factory'
-require 'mocha/ruby_version'
 
 module Mocha
   # Traditional mock object.
@@ -330,13 +328,6 @@ def respond_to_missing?(symbol, include_all)
       end
     end
 
-    if PRE_RUBY_V19
-      # @private
-      def respond_to?(symbol, include_all = false)
-        respond_to_missing?(symbol, include_all)
-      end
-    end
-
     # @private
     def __verified__?(assertion_counter = nil)
       @expectations.verified?(assertion_counter)
diff --git a/lib/mocha/mockery.rb b/lib/mocha/mockery.rb
index 64799c7d9..8aa0020bb 100644
--- a/lib/mocha/mockery.rb
+++ b/lib/mocha/mockery.rb
@@ -1,4 +1,3 @@
-require 'mocha/ruby_version'
 require 'mocha/central'
 require 'mocha/mock'
 require 'mocha/names'
@@ -119,7 +118,7 @@ def mocha_inspect
     end
 
     def on_stubbing(object, method)
-      method = PRE_RUBY_V19 ? method.to_s : method.to_sym
+      method = method.to_sym
       signature_proc = lambda { "#{object.mocha_inspect}.#{method}" }
       check(:stubbing_non_existent_method, 'non-existent method', signature_proc) do
         !(object.stubba_class.__method_exists__?(method, true) || object.respond_to?(method.to_sym))
diff --git a/lib/mocha/ruby_version.rb b/lib/mocha/ruby_version.rb
index c5c672c5e..01a74d05b 100644
--- a/lib/mocha/ruby_version.rb
+++ b/lib/mocha/ruby_version.rb
@@ -1,4 +1,3 @@
 module Mocha
-  PRE_RUBY_V19 = Gem::Version.new(RUBY_VERSION.dup) < Gem::Version.new('1.9')
   RUBY_V2_PLUS = Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2')
 end
diff --git a/lib/mocha/singleton_class.rb b/lib/mocha/singleton_class.rb
deleted file mode 100644
index 607d464e5..000000000
--- a/lib/mocha/singleton_class.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-if Gem::Version.new(RUBY_VERSION.dup) < Gem::Version.new('1.9.2')
-  unless Kernel.method_defined?(:singleton_class)
-    module Kernel
-      def singleton_class
-        class << self; self; end
-      end
-    end
-  end
-end
diff --git a/lib/mocha/stubbed_method.rb b/lib/mocha/stubbed_method.rb
index 48a1e17b1..95b64f5fa 100644
--- a/lib/mocha/stubbed_method.rb
+++ b/lib/mocha/stubbed_method.rb
@@ -1,5 +1,4 @@
 require 'mocha/ruby_version'
-require 'mocha/singleton_class'
 
 module Mocha
   class StubbedMethod
@@ -11,7 +10,7 @@ def initialize(stubbee, method_name)
       @stubbee = stubbee
       @original_method = nil
       @original_visibility = nil
-      @method_name = PRE_RUBY_V19 ? method_name.to_s : method_name.to_sym
+      @method_name = method_name.to_sym
     end
 
     def stub
diff --git a/mocha.gemspec b/mocha.gemspec
index a155d9ae8..5d3caab8b 100644
--- a/mocha.gemspec
+++ b/mocha.gemspec
@@ -6,7 +6,7 @@ Gem::Specification.new do |s|
   s.name = 'mocha'
   s.version = Mocha::VERSION
   s.licenses = ['MIT', 'BSD-2-Clause']
-  s.required_ruby_version = '>= 1.8.7'
+  s.required_ruby_version = '>= 1.9'
 
   s.authors = ['James Mead']
   s.description = 'Mocking and stubbing library with JMock/SchMock syntax, which allows mocking and stubbing of methods on real (non-mock) classes.'
diff --git a/test/acceptance/stub_method_defined_on_module_and_aliased_test.rb b/test/acceptance/stub_method_defined_on_module_and_aliased_test.rb
index e7f607502..2047d6cc6 100644
--- a/test/acceptance/stub_method_defined_on_module_and_aliased_test.rb
+++ b/test/acceptance/stub_method_defined_on_module_and_aliased_test.rb
@@ -1,38 +1,36 @@
 require File.expand_path('../acceptance_test_helper', __FILE__)
 
-unless Mocha::PRE_RUBY_V19
-  class StubMethodDefinedOnModuleAndAliasedTest < Mocha::TestCase
-    include AcceptanceTest
+class StubMethodDefinedOnModuleAndAliasedTest < Mocha::TestCase
+  include AcceptanceTest
 
-    def setup
-      setup_acceptance_test
-    end
+  def setup
+    setup_acceptance_test
+  end
 
-    def teardown
-      teardown_acceptance_test
-    end
+  def teardown
+    teardown_acceptance_test
+  end
 
-    def test_stubbing_class_method_defined_by_aliasing_module_instance_method
-      mod = Module.new do
-        def module_instance_method
-          'module-instance-method'
-        end
+  def test_stubbing_class_method_defined_by_aliasing_module_instance_method
+    mod = Module.new do
+      def module_instance_method
+        'module-instance-method'
       end
+    end
 
-      klass = Class.new do
-        extend mod
-        class << self
-          alias_method :aliased_module_instance_method, :module_instance_method
-        end
+    klass = Class.new do
+      extend mod
+      class << self
+        alias_method :aliased_module_instance_method, :module_instance_method
       end
+    end
 
-      assert_snapshot_unchanged(klass) do
-        test_result = run_as_test do
-          klass.stubs(:aliased_module_instance_method).returns('stubbed-aliased-module-instance-method')
-          assert_equal 'stubbed-aliased-module-instance-method', klass.aliased_module_instance_method
-        end
-        assert_passed(test_result)
+    assert_snapshot_unchanged(klass) do
+      test_result = run_as_test do
+        klass.stubs(:aliased_module_instance_method).returns('stubbed-aliased-module-instance-method')
+        assert_equal 'stubbed-aliased-module-instance-method', klass.aliased_module_instance_method
       end
+      assert_passed(test_result)
     end
   end
 end
diff --git a/test/assertions.rb b/test/assertions.rb
index daed7dabe..9d5f61e2d 100644
--- a/test/assertions.rb
+++ b/test/assertions.rb
@@ -1,8 +1,6 @@
-require 'mocha/ruby_version'
-
 module Assertions
   def assert_method_visibility(object, method_name, visiblity)
-    method_key = Mocha::PRE_RUBY_V19 ? method_name.to_s : method_name.to_sym
+    method_key = method_name.to_sym
     assert object.send("#{visiblity}_methods").include?(method_key), "#{method_name} is not #{visiblity}"
   end
 end
diff --git a/test/method_definer.rb b/test/method_definer.rb
index 1f5073946..bd0050a42 100644
--- a/test/method_definer.rb
+++ b/test/method_definer.rb
@@ -1,5 +1,3 @@
-require 'mocha/singleton_class'
-
 module MethodDefiner
   def define_instance_method(object, method_symbol, &block)
     object.singleton_class.send(:define_method, method_symbol, block)
diff --git a/test/unit/any_instance_method_test.rb b/test/unit/any_instance_method_test.rb
index 426afa27d..6f1cf6df0 100644
--- a/test/unit/any_instance_method_test.rb
+++ b/test/unit/any_instance_method_test.rb
@@ -1,4 +1,5 @@
 require File.expand_path('../../test_helper', __FILE__)
+require 'mocha/ruby_version'
 require 'method_definer'
 require 'mocha/class_methods'
 require 'mocha/mock'
@@ -65,7 +66,7 @@ def test_should_include_the_filename_and_line_number_in_exceptions
     method.define_new_method
 
     expected_filename = 'stubbed_method.rb'
-    expected_line_number = 61
+    expected_line_number = 60
 
     exception = assert_raises(Exception) { klass.new.method_x }
     matching_line = exception.backtrace.find do |line|
diff --git a/test/unit/instance_method_test.rb b/test/unit/instance_method_test.rb
index f903c09e0..0176c3130 100644
--- a/test/unit/instance_method_test.rb
+++ b/test/unit/instance_method_test.rb
@@ -1,8 +1,8 @@
 require File.expand_path('../../test_helper', __FILE__)
+require 'mocha/ruby_version'
 require 'method_definer'
 require 'mocha/class_methods'
 require 'mocha/mock'
-require 'mocha/singleton_class'
 
 require 'mocha/instance_method'
 
@@ -70,7 +70,7 @@ def test_should_include_the_filename_and_line_number_in_exceptions
     method.define_new_method
 
     expected_filename = 'stubbed_method.rb'
-    expected_line_number = 61
+    expected_line_number = 60
 
     exception = assert_raises(Exception) { klass.method_x }
     matching_line = exception.backtrace.find do |line|
diff --git a/test/unit/mock_test.rb b/test/unit/mock_test.rb
index 36aa0e597..ac0dd8af7 100644
--- a/test/unit/mock_test.rb
+++ b/test/unit/mock_test.rb
@@ -1,5 +1,4 @@
 require File.expand_path('../../test_helper', __FILE__)
-require 'mocha/ruby_version'
 require 'mocha/macos_version'
 require 'mocha/mock'
 require 'mocha/expectation_error_factory'
@@ -45,16 +44,10 @@ def test_should_be_equal
     assert_equal true, mock.eql?(mock)
   end
 
-  PRE_RUBY_V19_EXCLUDED_METHODS = %w[
-    method_missing
-    singleton_method_undefined
-    initialize
-  ].freeze
-
   MACOS_EXCLUDED_METHODS =
     MACOS && MACOS_VERSION >= MACOS_MOJAVE_VERSION ? [:syscall] : []
 
-  RUBY_V19_AND_LATER_EXCLUDED_METHODS = [
+  EXCLUDED_METHODS = [
     :object_id,
     :method_missing,
     :singleton_method_undefined,
@@ -65,9 +58,7 @@ def test_should_be_equal
   ].freeze
 
   OBJECT_METHODS = STANDARD_OBJECT_PUBLIC_INSTANCE_METHODS.reject do |m|
-    (m =~ /^__.*__$/) ||
-      (PRE_RUBY_V19 && PRE_RUBY_V19_EXCLUDED_METHODS.include?(m)) ||
-      (!PRE_RUBY_V19 && RUBY_V19_AND_LATER_EXCLUDED_METHODS.include?(m))
+    (m =~ /^__.*__$/) || EXCLUDED_METHODS.include?(m)
   end
 
   def test_should_be_able_to_mock_standard_object_methods
@@ -350,12 +341,10 @@ def test_should_remove_expectations_for_unstubbed_methods
     assert_match(/unexpected invocation/, e.message)
   end
 
-  unless PRE_RUBY_V19
-    def test_expectation_is_defined_on_mock
-      mock = build_mock
-      mock.expects(:method1)
-      assert defined? mock.method1
-    end
+  def test_expectation_is_defined_on_mock
+    mock = build_mock
+    mock.expects(:method1)
+    assert defined? mock.method1
   end
 
   private
diff --git a/test/unit/object_inspect_test.rb b/test/unit/object_inspect_test.rb
index 2abe90eb2..203fcfa67 100755
--- a/test/unit/object_inspect_test.rb
+++ b/test/unit/object_inspect_test.rb
@@ -1,5 +1,4 @@
 require File.expand_path('../../test_helper', __FILE__)
-require 'mocha/ruby_version'
 require 'mocha/inspect'
 require 'method_definer'
 
@@ -27,12 +26,6 @@ class << object
   def test_should_use_underscored_id_instead_of_object_id_or_id_so_that_they_can_be_stubbed
     calls = []
     object = Object.new
-    if Mocha::PRE_RUBY_V19
-      replace_instance_method(object, :id) do
-        calls << :id
-        return 1
-      end
-    end
     replace_instance_method(object, :object_id) do
       calls << :object_id
       return 1