diff --git a/.ruby-version b/.ruby-version
deleted file mode 100644
index 6a6a3d8e..00000000
--- a/.ruby-version
+++ /dev/null
@@ -1 +0,0 @@
-2.6.1
diff --git a/Gemfile b/Gemfile
index 8e5c8738..25f24a1b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -17,6 +17,7 @@ group :test do
   gem "minitest-color"
   gem 'minitest-fail-fast'
   gem 'minitest-profile'
+  gem "minitest-parallel_fork" , require: false
 end
 
 group :development do
diff --git a/test/test_all.rb b/test/test_all.rb
index 6716c02e..bd2b772e 100755
--- a/test/test_all.rb
+++ b/test/test_all.rb
@@ -1,7 +1,5 @@
 ENV["TEST_ALL"] = "true"
 require_relative "helper"
+require "minitest/parallel_fork" if ENV["NCPU"]
 
-Dir["test/**/test_*.rb"].each { |f|
-  next if f.include?("stash/")
-  require_relative "../#{f}"
-}
+Dir["test/**/test_*.rb"].each { |f|  require_relative "../#{f}" }