diff --git a/.gitignore b/.gitignore
index c22f19c..1fa0230 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,4 @@ mkmf.log
 **/*.swp
 **/*.gem
 .idea
+/rubyspec_temp/
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..072bbc6
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "spec/ruby_spec"]
+	path = spec/ruby_spec
+	url = https://github.com/ruby/spec
diff --git a/Gemfile b/Gemfile
index b806447..762b189 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,7 @@
-source 'https://rubygems.org'
+source 'https://rubygems.org' do
+  # Specify your gem's dependencies in faster_path.gemspec
+  gemspec
+end
 
-# Specify your gem's dependencies in faster_path.gemspec
-gemspec
+# https://github.com/ruby/spec dependencies
+eval_gemfile File.expand_path('spec/ruby_spec/Gemfile', File.dirname(__FILE__))
diff --git a/README.md b/README.md
index d242229..d2a007f 100644
--- a/README.md
+++ b/README.md
@@ -117,7 +117,7 @@ And then execute:
 Or install it yourself as:
 
     $ gem install faster_path
-    
+
 **MAC USERS:** At the moment Mac users need to install the extension manualy.  Go to the gem directory and run `cargo build --release` .  There is an issue opened for this and I'm looking for people who have Macs to help on this.
 
 ## Usage
@@ -136,7 +136,7 @@ Current methods implemented:
 | `FasterPath.extname` | `File#extname` | 11.2% |
 
 You may choose to use the methods directly, or scope change to rewrite behavior on the
-standard library with the included refinements, or even call a method to monkeypatch 
+standard library with the included refinements, or even call a method to monkeypatch
 everything everywhere.
 
 **Note:** `Pathname#chop_basename` in Ruby STDLIB has a bug with blank strings, that is the
@@ -184,6 +184,42 @@ Then, run `rake test` to run the tests, and `rake bench` for benchmarks.
 
 Learn and share performance tips on the [wiki](https://github.com/danielpclark/faster_path/wiki)!
 
+### Building and running tests
+
+First, bundle the gem's development dependencies by running `bundle`.
+
+Then, build the rust code:
+
+```sh
+rake build_src
+```
+
+FasterPath is tested with [The Ruby Spec Suite](https://github.com/ruby/spec) to ensure it is compatible with the
+native implementation, and also has its own test suite testing its monkey-patching and refinements functionality.
+
+To run all the tests at once, simply run `rake`.
+To run all the ruby spec tests, run `mspec`.
+
+To run an individual test or benchmark from FasterPath's own suite:
+
+```sh
+# An individual test file:
+ruby -I lib:test test/benches/absolute_benchmark.rb
+# All tests:
+rake minitest
+```
+
+To run an individual ruby spec test, run `mspec` with a path relative to `spec/ruby_spec`, e.g.:
+
+```sh
+# A path to a file or a directory:
+mspec core/file/basename_spec.rb
+# Tests most relevant to FasterPath:
+mspec core/file library/pathname
+# All tests:
+mspec
+```
+
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/danielpclark/faster_path.
diff --git a/Rakefile b/Rakefile
index 7a19857..6fbd8da 100644
--- a/Rakefile
+++ b/Rakefile
@@ -27,12 +27,16 @@ task :build_lib => [:build_src, :clean_src] do
   puts "Completed build!"
 end
 
-Rake::TestTask.new(:test) do |t|
+Rake::TestTask.new(:minitest) do |t|
   t.libs << "test"
   t.libs << "lib"
   t.test_files = FileList['test/**/*_test.rb']
 end
 
+task :test => :minitest do |t|
+  exec 'mspec core/file library/pathname'
+end
+
 Rake::TestTask.new(:bench) do |t|
   t.libs = %w(lib test)
   t.pattern = 'test/**/*_benchmark.rb'
diff --git a/lib/faster_path/optional/monkeypatches.rb b/lib/faster_path/optional/monkeypatches.rb
index d0ea164..b7e831b 100644
--- a/lib/faster_path/optional/monkeypatches.rb
+++ b/lib/faster_path/optional/monkeypatches.rb
@@ -1,3 +1,5 @@
+require 'pathname'
+
 module FasterPath
   def self.sledgehammer_everything!
     ::File.class_eval do
diff --git a/spec/default.mspec b/spec/default.mspec
new file mode 100644
index 0000000..b8e3c6d
--- /dev/null
+++ b/spec/default.mspec
@@ -0,0 +1,8 @@
+load 'spec/ruby_spec/default.mspec'
+
+class MSpecScript
+  set :requires, ["-r#{File.expand_path('init', File.dirname(__FILE__))}"]
+  set :prefix, 'spec/ruby_spec'
+end
+
+MSpec.disable_feature :encoding
diff --git a/spec/init.rb b/spec/init.rb
new file mode 100644
index 0000000..afe0b11
--- /dev/null
+++ b/spec/init.rb
@@ -0,0 +1,5 @@
+ENV['BUNDLE_GEMFILE'] = File.expand_path('../Gemfile', File.dirname(__FILE__))
+$LOAD_PATH.unshift File.expand_path('../lib', File.dirname(__FILE__))
+require 'faster_path'
+require 'faster_path/optional/monkeypatches'
+FasterPath.sledgehammer_everything!
diff --git a/spec/ruby_spec b/spec/ruby_spec
new file mode 160000
index 0000000..8190a7c
--- /dev/null
+++ b/spec/ruby_spec
@@ -0,0 +1 @@
+Subproject commit 8190a7c915fbcf4776b99390418fe63fc6086c02