diff --git a/doc/maintainers.rdoc b/doc/maintainers.rdoc
index 81099817f2..5a99d81912 100644
--- a/doc/maintainers.rdoc
+++ b/doc/maintainers.rdoc
@@ -102,8 +102,6 @@ Zachary Scott (zzak)
   Tanaka Akira (akr)
 [lib/prettyprint.rb]
   Tanaka Akira (akr)
-[lib/prime.rb]
-  Yuki Sonoda (yugui)
 [lib/profile.rb]
   _unmaintained_
 [lib/profiler.rb]
@@ -213,6 +211,8 @@ Zachary Scott (zzak)
   https://github.com/ruby/fileutils
 [lib/logger.rb]
   Naotoshi Seo (sonots)
+[lib/prime.rb]
+  Yuki Sonoda (yugui)
 [lib/rdoc.rb, lib/rdoc/*]
   Eric Hodel (drbrain), Hiroshi SHIBATA (hsbt)
   https://github.com/ruby/rdoc
diff --git a/doc/standard_library.rdoc b/doc/standard_library.rdoc
index 6aaa32c761..692859775e 100644
--- a/doc/standard_library.rdoc
+++ b/doc/standard_library.rdoc
@@ -40,7 +40,6 @@ OptionParser:: Ruby-oriented class for command-line option analysis
 OpenStruct:: Class to build custom data structures, similar to a Hash
 PP:: Provides a PrettyPrinter for Ruby objects
 PrettyPrinter:: Implements a pretty printing algorithm for readable structure
-Prime:: Prime numbers and factorization library
 profile.rb:: Runs the Ruby Profiler__
 Profiler__:: Provides a way to profile your Ruby application
 PStore:: Implements a file based persistence mechanism based on a Hash
@@ -93,6 +92,7 @@ CMath:: Provides Trigonometric and Transcendental functions for complex numbers
 CSV:: Provides an interface to read and write CSV files and data
 FileUtils:: Several file utility methods for copying, moving, removing, etc
 Logger:: Provides a simple logging utility for outputting messages
+Prime:: Prime numbers and factorization library
 RDoc:: Produces HTML and command-line documentation for Ruby
 REXML:: An XML toolkit for Ruby
 RSS:: Family of libraries that support various formats of XML "feeds"
diff --git a/lib/prime.gemspec b/lib/prime.gemspec
new file mode 100644
index 0000000000..de6d4f93b9
--- /dev/null
+++ b/lib/prime.gemspec
@@ -0,0 +1,22 @@
+require_relative "prime"
+
+Gem::Specification.new do |spec|
+  spec.name          = "prime"
+  spec.version       = Prime::VERSION
+  spec.authors       = ["Yuki Sonoda"]
+  spec.email         = ["yugui@yugui.jp"]
+
+  spec.summary       = %q{Prime numbers and factorization library.}
+  spec.description   = %q{Prime numbers and factorization library.}
+  spec.homepage      = "https://github.com/ruby/prime"
+  spec.license       = "BSD-2-Clause"
+
+  spec.files         = [".gitignore", ".travis.yml", "Gemfile", "LICENSE.txt", "README.md", "Rakefile", "bin/console", "bin/setup", "lib/prime.rb", "lib/prime/version.rb", "prime.gemspec"]
+  spec.bindir        = "exe"
+  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"
+end
diff --git a/lib/prime.rb b/lib/prime.rb
index 2cd22da3a8..4fcbff678f 100644
--- a/lib/prime.rb
+++ b/lib/prime.rb
@@ -95,6 +95,9 @@ end
 #   has many prime factors. e.g. for Prime#prime? .
 
 class Prime
+
+  VERSION = "0.1.0"
+
   include Enumerable
   include Singleton