Added support for binary gems.
diff --git a/ruby/Rakefile b/ruby/Rakefile
index c25103d..44497de 100644
--- a/ruby/Rakefile
+++ b/ruby/Rakefile
@@ -21,6 +21,11 @@
     ext.ext_dir = "ext/google/protobuf_c"
     ext.lib_dir = "lib/google"
   end
+
+  task 'gem:windows' do
+    require 'rake_compiler_dock'
+    RakeCompilerDock.sh "bundle && rake cross native gem"
+  end
 end
 
 Gem::PackageTask.new(spec) do |pkg|