diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..f46b48e
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,21 @@
+name: ubuntu
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ 'ubuntu-latest', 'macos-latest', 'windows-latest' ]
+        ruby: [ 'head', '2.7', '2.6', '2.5' ]
+    steps:
+    - uses: actions/checkout@master
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
+    - name: Install dependencies
+      run: bundle install
+    - name: Run test
+      run: rake test
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index a7b4916..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-sudo: false
-language: ruby
-rvm:
-  - 2.5.1
-  - ruby-head
-before_install: gem install bundler -v 1.16.2
diff --git a/Gemfile b/Gemfile
index 901dccc..9d226e0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,5 +2,9 @@ source "https://rubygems.org"
 
 git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
-# Specify your gem's dependencies in prime.gemspec
 gemspec
+
+group :development do
+  gem "rake"
+  gem "test-unit"
+end
diff --git a/lib/prime.rb b/lib/prime.rb
index cf08be0..d2de8dc 100644
--- a/lib/prime.rb
+++ b/lib/prime.rb
@@ -96,7 +96,7 @@ def Integer.each_prime(ubound, &block) # :yields: prime
 
 class Prime
 
-  VERSION = "0.1.0"
+  VERSION = "0.1.1"
 
   include Enumerable
   include Singleton
diff --git a/prime.gemspec b/prime.gemspec
index 6a9aa68..aa7fe6f 100644
--- a/prime.gemspec
+++ b/prime.gemspec
@@ -21,7 +21,5 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_development_dependency "bundler"
-  spec.add_development_dependency "rake"
-  spec.add_development_dependency "test-unit"
+  spec.required_ruby_version = ">= 2.5.0"
 end