diff --git a/Gemfile b/Gemfile
index 59f77c9d..dd3185b6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -53,7 +53,13 @@ group :bench do
 end
 
 group :test do
-  gem 'sqlite3', '~> 1.3.13', platform: (@windows_platforms + [:ruby])
+  platforms *(@windows_platforms + [:ruby]) do
+    if version == 'master' || version >= '6'
+      gem 'sqlite3', '~> 1.4'
+    else
+      gem 'sqlite3', '~> 1.3.13'
+    end
+  end
   platforms :jruby do
     if version == 'master' || version >= '5'
       gem 'activerecord-jdbcsqlite3-adapter', '~> 50'
diff --git a/test/support/ruby_2_6_rails_4_2_patch.rb b/test/support/ruby_2_6_rails_4_2_patch.rb
new file mode 100644
index 00000000..e4de2432
--- /dev/null
+++ b/test/support/ruby_2_6_rails_4_2_patch.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+if RUBY_VERSION >= '2.6.0'
+  if Rails::VERSION::MAJOR < 5
+    class ActionController::TestResponse < ActionDispatch::TestResponse
+      def recycle!
+        # hack to avoid MonitorMixin double-initialize error:
+        @mon_mutex_owner_object_id = nil
+        @mon_mutex = nil
+        initialize
+      end
+    end
+  else
+    puts "Monkeypatch for ActionController::TestResponse no longer needed"
+  end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 80996494..e8f60cc9 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -56,6 +56,8 @@ end
 
 require 'support/rails_app'
 
+require 'support/ruby_2_6_rails_4_2_patch'
+
 # require "rails/test_help"
 
 require 'support/serialization_testing'