diff --git a/Gemfile b/Gemfile
index 8d93ebc..ba9393b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,6 +3,9 @@ source 'http://rubygems.org'
 # Specify your gem's dependencies in child_process.gemspec
 gemspec
 
+# Used for local development/testing only
+gem 'rake'
+
 if RUBY_VERSION =~ /^1\./
   gem 'tins', '< 1.7' # The 'tins' gem requires Ruby 2.x on/after this version
   gem 'json', '< 2.0' # The 'json' gem drops pre-Ruby 2.x support on/after this version
diff --git a/README.md b/README.md
index 952fc00..3875914 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,8 @@ a standalone library.
 
 * Ruby 2.3+, JRuby 9+
 
+Windows users **must** ensure the `ffi` gem (`>= 1.0.11`) is installed in order to use ChildProcess.
+
 # Usage
 
 The object returned from `ChildProcess.build` will implement `ChildProcess::AbstractProcess`.
diff --git a/childprocess.gemspec b/childprocess.gemspec
index d52c2b1..2825838 100644
--- a/childprocess.gemspec
+++ b/childprocess.gemspec
@@ -23,9 +23,4 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rspec", "~> 3.0"
   s.add_development_dependency "yard", "~> 0.0"
   s.add_development_dependency 'coveralls', '< 1.0'
-
-  s.add_runtime_dependency 'rake', '< 13.0'
-
-  # Install FFI gem if we're running on Windows
-  s.extensions = 'ext/mkrf_conf.rb'
 end
diff --git a/ext/mkrf_conf.rb b/ext/mkrf_conf.rb
deleted file mode 100644
index 74e2266..0000000
--- a/ext/mkrf_conf.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-# Based on the example from https://en.wikibooks.org/wiki/Ruby_Programming/RubyGems#How_to_install_different_versions_of_gems_depending_on_which_version_of_ruby_the_installee_is_using
-require 'rubygems'
-require 'rubygems/command.rb'
-require 'rubygems/dependency_installer.rb'
-
-begin
-  Gem::Command.build_args = ARGV
-rescue NoMethodError # rubocop:disable Lint/HandleExceptions
-end
-
-inst = Gem::DependencyInstaller.new
-
-begin
-  if Gem.win_platform?
-    inst.install 'ffi', Gem::Requirement.new('~> 1.0', '>= 1.0.11')
-  end
-rescue # rubocop:disable Lint/RescueWithoutErrorClass
-  exit(1)
-end
-
- # create dummy rakefile to indicate success
-File.open(File.join(File.dirname(__FILE__), 'Rakefile'), 'w') do |f|
-  f.write("task :default\n")
-end