diff --git a/ruby-gem/calabash-android.gemspec b/ruby-gem/calabash-android.gemspec
index 31d65f78f..9256036ea 100644
--- a/ruby-gem/calabash-android.gemspec
+++ b/ruby-gem/calabash-android.gemspec
@@ -4,7 +4,8 @@ Gem::Specification.new do |s|
   s.name        = "calabash-android"
   s.version     = begin
     file = "#{File.expand_path(File.join(File.dirname(__FILE__),
-                                      "lib", "calabash-android", "version.rb"))}"
+                                         "lib", "calabash-android",
+                                         "version.rb"))}"
     m = Module.new
     m.module_eval IO.read(file).force_encoding("utf-8")
     version = m::Calabash::Android::VERSION
@@ -47,7 +48,6 @@ into a valid version, e.g. 1.2.3 or 1.2.3.pre10
   s.add_dependency( "awesome_print", '~> 1.2')
   s.add_dependency( 'httpclient', '>= 2.7.1', '< 3.0')
   s.add_dependency( 'escape', '~> 0.0.4')
-  s.add_dependency( 'luffa' )
 
   s.add_development_dependency( 'rake', '~> 10.3' )
   s.add_development_dependency( 'yard', '>= 0.9.12', '< 1.0' )
diff --git a/ruby-gem/lib/calabash-android/dependencies.rb b/ruby-gem/lib/calabash-android/dependencies.rb
index 694aa959e..eaa8c43da 100644
--- a/ruby-gem/lib/calabash-android/dependencies.rb
+++ b/ruby-gem/lib/calabash-android/dependencies.rb
@@ -1,5 +1,4 @@
 require 'rexml/document'
-require 'luffa'
 require 'timeout'
 
 if RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/
@@ -193,13 +192,13 @@ def self.tools_directories(android_sdk_location)
                 build_tools_directories =
                     build_tools_files.select do |dir|
                         begin
-                            Luffa::Version.new(File.basename(dir))
+                            Calabash::Android::Version.new(File.basename(dir))
                             true
                         rescue ArgumentError
                             false
                         end
                     end.sort do |a, b|
-                        Luffa::Version.compare(Luffa::Version.new(File.basename(a)), Luffa::Version.new(File.basename(b)))
+                        Calabash::Android::Version.compare(Calabash::Android::Version.new(File.basename(a)), Calabash::Android::Version.new(File.basename(b)))
                     end.reverse.map{|dir| File.join('build-tools', File.basename(dir))}
 
                 if build_tools_directories.empty?
diff --git a/ruby-gem/lib/calabash-android/version.rb b/ruby-gem/lib/calabash-android/version.rb
index fba8a1454..9dc4afa5d 100644
--- a/ruby-gem/lib/calabash-android/version.rb
+++ b/ruby-gem/lib/calabash-android/version.rb
@@ -1,5 +1,213 @@
 module Calabash
   module Android
     VERSION = "0.9.8"
+
+    # A model of a software release version that can be used to compare two versions.
+    #
+    # Calabash and RunLoop try very hard to comply with Semantic Versioning rules.
+    # However, the semantic versioning spec is incompatible with RubyGem's patterns
+    # for pre-release gems.
+    #
+    # > "But returning to the practical: No release version of SemVer is compatible
+    # > with Rubygems." - _David Kellum_
+    #
+    # Calabash and RunLoop version numbers will be in the form `<major>.<minor>.<patch>[.pre<N>]`.
+    #
+    # @see http://semver.org/
+    # @see http://gravitext.com/2012/07/22/versioning.html
+    #
+    # TODO Expand to handle versions with more than 1 "." and no "."
+    # ^ Needs to handle arbitrary versions from Info.plists.  In particular it
+    #   needs to handle a unix timestamp - found the DeviceAgent-Runner.app.
+    class Version
+
+      # @!attribute [rw] major
+      #   @return [Integer] the major version
+      attr_accessor :major
+
+      # @!attribute [rw] minor
+      #   @return [Integer] the minor version
+      attr_accessor :minor
+
+      # @!attribute [rw] patch
+      #   @return [Integer] the patch version
+      attr_accessor :patch
+
+      # @!attribute [rw] pre
+      #   @return [Boolean] true if this is a pre-release version
+      attr_accessor :pre
+
+      # @!attribute [rw] pre_version
+      #   @return [Integer] if this is a pre-release version, returns the
+      #     pre-release version; otherwise this is nil
+      attr_accessor :pre_version
+
+      # Creates a new Version instance with all the attributes set.
+      #
+      # @example
+      #  version = Version.new(0.10.1)
+      #  version.major       => 0
+      #  version.minor       => 10
+      #  version.patch       => 1
+      #  version.pre         => false
+      #  version.pre_version => nil
+      #
+      # @example
+      #  version = Version.new(1.6.3.pre5)
+      #  version.major       => 1
+      #  version.minor       => 6
+      #  version.patch       => 3
+      #  version.pre         => true
+      #  version.pre_version => 5
+      #
+      # @param [String] version the version string to parse.
+      # @raise [ArgumentError] if version is not in the form 5, 6.1, 7.1.2, 8.2.3.pre1
+      def initialize(version)
+        tokens = version.strip.split('.')
+        count = tokens.count
+        if tokens.empty?
+          raise ArgumentError, "expected '#{version}' to be like 5, 6.1, 7.1.2, 8.2.3.pre1"
+        end
+
+        if count < 4 and tokens.any? { |elm| elm =~ /\D/ }
+          raise ArgumentError, "expected '#{version}' to be like 5, 6.1, 7.1.2, 8.2.3.pre1"
+        end
+
+        if count == 4
+          @pre = tokens[3]
+          pre_tokens = @pre.scan(/\D+|\d+/)
+          @pre_version = pre_tokens[1].to_i if pre_tokens.count == 2
+        end
+
+        @major, @minor, @patch = version.split('.').map(&:to_i)
+      end
+
+      # Returns an string representation of this version.
+      # @return [String] a string in the form `<major>.<minor>.<patch>[.pre<N>]`
+      def to_s
+        str = [major, minor, patch].compact.join('.')
+        str = "#{str}.#{pre}" if pre
+        str
+      end
+
+      def inspect
+        "#<Version #{to_s}>"
+      end
+
+      # Compare this version to another for _object_ equality.  This allows
+      # Version instances to be used as Hash keys.
+      # @param [Version] other the version to compare against.
+      def eql?(other)
+        hash == other.hash
+      end
+
+      # The hash method for this instance.
+      def hash
+        str = [major, minor, patch].map do |str|
+          str ? str : "0"
+        end.join(".")
+
+        if pre
+          str = "#{str}.#{pre}"
+        end
+
+        str.hash
+      end
+
+      # Compare this version to another for equality.
+      # @param [Version] other the version to compare against
+      # @return [Boolean] true if this Version is the same as `other`
+      def == (other)
+        Version.compare(self, other) == 0
+      end
+
+      # Compare this version to another for inequality.
+      # @param [Version] other the version to compare against
+      # @return [Boolean] true if this Version is not the same as `other`
+      def != (other)
+        Version.compare(self, other) != 0
+      end
+
+      # Is this version less-than another version?
+      # @param [Version] other the version to compare against
+      # @return [Boolean] true if this Version is less-than `other`
+      def < (other)
+        Version.compare(self, other) < 0
+      end
+
+      # Is this version greater-than another version?
+      # @param [Version] other the version to compare against
+      # @return [Boolean] true if this Version is greater-than `other`
+      def > (other)
+        Version.compare(self, other) > 0
+      end
+
+      # Is this version less-than or equal to another version?
+      # @param [Version] other the version to compare against
+      # @return [Boolean] true if this Version is less-than or equal `other`
+      def <= (other)
+        Version.compare(self, other) <= 0
+      end
+
+      # Is this version greater-than or equal to another version?
+      # @param [Version] other the version to compare against
+      # @return [Boolean] true if this Version is greater-than or equal `other`
+      def >= (other)
+        Version.compare(self, other) >= 0
+      end
+
+      # Compare version `a` to version `b`.
+      #
+      # @example
+      #   compare Version.new(0.10.0), Version.new(0.9.0)  =>  1
+      #   compare Version.new(0.9.0),  Version.new(0.10.0) => -1
+      #   compare Version.new(0.9.0),  Version.new(0.9.0)  =>  0
+      #
+      # @return [Integer] an integer `(-1, 1)`
+      def <=> (other)
+        Version.compare(self, other)
+      end
+
+      # Compare version `a` to version `b`.
+      #
+      # @example
+      #   compare Version.new(0.10.0), Version.new(0.9.0)  =>  1
+      #   compare Version.new(0.9.0),  Version.new(0.10.0) => -1
+      #   compare Version.new(0.9.0),  Version.new(0.9.0)  =>  0
+      #
+      # @return [Integer] an integer `(-1, 1)`
+      def self.compare(a, b)
+
+        if a.major != b.major
+          return a.major.to_i > b.major.to_i ? 1 : -1
+        end
+
+        a_minor = a.minor ? a.minor.to_i : 0
+        b_minor = b.minor ? b.minor.to_i : 0
+        if a_minor != b_minor
+          return a_minor > b_minor.to_i ? 1 : -1
+        end
+
+        a_patch = a.patch ? a.patch.to_i : 0
+        b_patch = b.patch ? b.patch.to_i : 0
+        if a_patch != b_patch
+          return a_patch.to_i > b_patch.to_i ? 1 : -1
+        end
+
+        return -1 if a.pre && (!a.pre_version) && b.pre_version
+        return 1 if a.pre_version && b.pre && (!b.pre_version)
+
+        return -1 if a.pre && (!b.pre)
+        return 1 if (!a.pre) && b.pre
+
+        return -1 if a.pre_version && (!b.pre_version)
+        return 1 if (!a.pre_version) && b.pre_version
+
+        if a.pre_version != b.pre_version
+          return a.pre_version.to_i > b.pre_version.to_i ? 1 : -1
+        end
+        0
+      end
+    end
   end
 end
diff --git a/ruby-gem/spec/lib/version_spec.rb b/ruby-gem/spec/lib/version_spec.rb
new file mode 100644
index 000000000..77236a3ac
--- /dev/null
+++ b/ruby-gem/spec/lib/version_spec.rb
@@ -0,0 +1,297 @@
+describe Calabash::Android::Version do
+
+  describe '.new' do
+    describe 'non-pre-release versions' do
+      subject(:version) { Calabash::Android::Version.new('0.9.169') }
+      it { expect(version).not_to be nil }
+      it { expect(version.major).to be == 0 }
+      it { expect(version.minor).to be == 9 }
+      it { expect(version.patch).to be == 169 }
+      it { expect(version.pre).to be nil }
+      it { expect(version.pre_version).to be nil }
+    end
+
+    describe 'unnumbered pre-release versions' do
+      subject(:version) { Calabash::Android::Version.new('0.9.169.pre') }
+      it { expect(version.pre).to be == 'pre' }
+      it { expect(version.pre_version).to be nil }
+    end
+
+    describe 'numbered pre-release versions' do
+      subject(:version) { Calabash::Android::Version.new('0.9.169.pre1') }
+      it { expect(version.pre).to be == 'pre1' }
+      it { expect(version.pre_version).to be == 1 }
+    end
+
+    describe 'invalid arguments' do
+      it { expect { Calabash::Android::Version.new(' ') }.to raise_error ArgumentError }
+      it { expect { Calabash::Android::Version.new('5.1.pre3') }.to raise_error ArgumentError }
+      it { expect { Calabash::Android::Version.new('5.pre2') }.to raise_error ArgumentError }
+    end
+  end
+
+  describe '#hash' do
+    it '0.9.5.pre1' do
+      str = '0.9.5.pre1'
+      version = Calabash::Android::Version.new(str)
+      expect(str.hash).to be == version.hash
+    end
+
+    it '0.9.5.pre' do
+      str = '0.9.5.pre'
+      version = Calabash::Android::Version.new(str)
+      expect(str.hash).to be == version.hash
+    end
+
+    it '0.9.5' do
+      str = '0.9.5'
+      version = Calabash::Android::Version.new(str)
+      expect(str.hash).to be == version.hash
+    end
+
+    it '0.9' do
+      version = Calabash::Android::Version.new("0.9")
+      expect("0.9.0".hash).to be == version.hash
+    end
+
+    it '0' do
+      version = Calabash::Android::Version.new("0")
+      expect("0.0.0".hash).to be == version.hash
+    end
+
+    it "9 == 9.0 == 9.0.0" do
+      version = Calabash::Android::Version.new("9")
+      expect("9.0.0".hash).to be == version.hash
+
+      version = Calabash::Android::Version.new("9.0")
+      expect("9.0.0".hash).to be == version.hash
+    end
+  end
+
+  describe '#eql?' do
+    it 'mocked' do
+      a = Calabash::Android::Version.new('9.9.9')
+      b = Calabash::Android::Version.new('0.0.0')
+
+      expect(a).to receive(:hash).and_return(-1, -1)
+      expect(b).to receive(:hash).and_return(-1, 0)
+
+      expect(a.eql?(b)).to be == true
+      expect(a.eql?(b)).to be == false
+    end
+
+    it 'are equal' do
+
+      a = Calabash::Android::Version.new('0.0.0')
+      b = Calabash::Android::Version.new('0.0.0')
+
+      expect(a.eql?(b)).to be == true
+    end
+
+    it 'are not equal' do
+
+      a = Calabash::Android::Version.new('9.9.9')
+      b = Calabash::Android::Version.new('0.0.0')
+
+      expect(a.eql?(b)).to be == false
+    end
+  end
+
+  describe 'instance as a hash key' do
+    it 'keys match' do
+      a = Calabash::Android::Version.new('0.0.0')
+      b = Calabash::Android::Version.new('0.0.0')
+
+      hash = { a => 'before!' }
+
+      hash[b] = 'after!'
+      expect(hash[a]) == 'after!'
+    end
+
+    it 'keys do not match' do
+      a = Calabash::Android::Version.new('0.0.0')
+      b = Calabash::Android::Version.new('9.9.9')
+
+      hash = { a => 'before!' }
+
+      hash[b] = 'after!'
+      expect(hash[a]) == 'before!'
+      expect(hash[b]) == 'after!'
+    end
+  end
+
+  describe '==' do
+    it 'tests equality' do
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5')
+      expect(a == b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre')
+      b = Calabash::Android::Version.new('0.9.5.pre')
+      expect(a == b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre1')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a == b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a == b).to be false
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a == b).to be false
+
+      a = Calabash::Android::Version.new("9.0.0")
+      b = Calabash::Android::Version.new("9")
+      expect(b == a).to be true
+
+      a = Calabash::Android::Version.new("9")
+      b = Calabash::Android::Version.new("9.0")
+      expect(b == a).to be true
+
+      a = Calabash::Android::Version.new("9.0.0")
+      b = Calabash::Android::Version.new("9.0")
+      expect(b == a).to be true
+    end
+  end
+
+  describe '!=' do
+    it 'tests not equal' do
+      a = Calabash::Android::Version.new('0.9.4')
+      b = Calabash::Android::Version.new('0.9.5')
+      expect(a != b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre')
+      expect(a != b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a != b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a != b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre1')
+      b = Calabash::Android::Version.new('0.9.5.pre2')
+      expect(a != b).to be true
+    end
+  end
+
+  describe '<' do
+    it 'tests less than' do
+      a = Calabash::Android::Version.new('0.9.4')
+      b = Calabash::Android::Version.new('0.9.5')
+      expect(a < b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre')
+      expect(a > b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a > b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(a < b).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre1')
+      b = Calabash::Android::Version.new('0.9.5.pre2')
+      expect(a < b).to be true
+    end
+  end
+
+  describe '>' do
+    it 'tests greater than' do
+      a = Calabash::Android::Version.new('0.9.4')
+      b = Calabash::Android::Version.new('0.9.5')
+      expect(b > a).to be true
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre')
+      expect(b < a).to be true
+
+      a = Calabash::Android::Version.new('0.9.5')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(b < a).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre')
+      b = Calabash::Android::Version.new('0.9.5.pre1')
+      expect(b > a).to be true
+
+      a = Calabash::Android::Version.new('0.9.5.pre1')
+      b = Calabash::Android::Version.new('0.9.5.pre2')
+      expect(b > a).to be true
+
+      a = Calabash::Android::Version.new("8.0")
+      b = Calabash::Android::Version.new("9.0")
+      expect(a > b).to be false
+
+      a = Calabash::Android::Version.new("9.0")
+      b = Calabash::Android::Version.new("8.0")
+      expect(a > b).to be true
+    end
+  end
+
+  describe '<=' do
+    it 'tests less-than or equal' do
+      a = Calabash::Android::Version.new('0.9.4')
+      b = Calabash::Android::Version.new('0.9.5')
+      expect(a <= b).to be true
+      a = Calabash::Android::Version.new('0.9.5')
+      expect(a <= b).to be true
+
+      a = Calabash::Android::Version.new("9.0.0")
+      b = Calabash::Android::Version.new("9")
+      expect(b <= a).to be true
+
+      a = Calabash::Android::Version.new("9.0")
+      b = Calabash::Android::Version.new("9")
+      expect(b <= a).to be true
+
+      a = Calabash::Android::Version.new("9.0.0")
+      b = Calabash::Android::Version.new("9.0")
+      expect(b <= a).to be true
+    end
+  end
+
+  describe '>=' do
+    it 'tests greater-than or equal' do
+      a = Calabash::Android::Version.new('0.9.4')
+      b = Calabash::Android::Version.new('0.9.5')
+      expect(b >= a).to be true
+      a = Calabash::Android::Version.new('0.9.5')
+      expect(b >= a).to be true
+
+      a = Calabash::Android::Version.new("9.0.0")
+      b = Calabash::Android::Version.new("9")
+      expect(b >= a).to be true
+
+      a = Calabash::Android::Version.new("9.0")
+      b = Calabash::Android::Version.new("9")
+      expect(b >= a).to be true
+
+      a = Calabash::Android::Version.new("9.0.0")
+      b = Calabash::Android::Version.new("9.0")
+      expect(b >= a).to be true
+    end
+  end
+
+  describe '.compare' do
+    subject(:a) {  Calabash::Android::Version.new('6.0')  }
+    it 'works if there is no patch level' do
+      b = Calabash::Android::Version.new('5.1.1')
+      expect(Calabash::Android::Version.compare(a, b)).to be  == 1
+      expect(Calabash::Android::Version.compare(b, a)).to be  == -1
+    end
+
+    it 'works if there is no minor level' do
+      b = Calabash::Android::Version.new('5')
+      expect(Calabash::Android::Version.compare(a, b)).to be == 1
+      expect(Calabash::Android::Version.compare(b, a)).to be == -1
+    end
+  end
+end