diff --git a/c/unpack.c b/c/unpack.c
index d5bcb2d9..140ad1f1 100644
--- a/c/unpack.c
+++ b/c/unpack.c
@@ -52,7 +52,7 @@ static int template_execute(template_context* ctx,
 
 
 static inline msgpack_object template_callback_root(unpack_user* u)
-{ msgpack_object o; return o; }
+{ msgpack_object o = {0}; return o; }
 
 static inline int template_callback_uint8(unpack_user* u, uint8_t d, msgpack_object* o)
 { o->type = MSGPACK_OBJECT_POSITIVE_INTEGER; o->via.u64 = d; return 0; }
diff --git a/configure.in b/configure.in
index 259ed377..c75957b2 100644
--- a/configure.in
+++ b/configure.in
@@ -1,6 +1,6 @@
 AC_INIT(msgpack/unpack_template.h)
 AC_CONFIG_AUX_DIR(ac)
-AM_INIT_AUTOMAKE(msgpack, 0.4.1)
+AM_INIT_AUTOMAKE(msgpack, 0.4.2)
 AC_CONFIG_HEADER(config.h)
 
 AC_SUBST(CFLAGS)
diff --git a/ruby/makegem.sh b/ruby/makegem.sh
index fd0db790..622264de 100755
--- a/ruby/makegem.sh
+++ b/ruby/makegem.sh
@@ -19,3 +19,8 @@ cat msgpack_test.rb | sed "s/require ['\"]msgpack['\"]/require File.dirname(__FI
 
 gem build msgpack.gemspec
 
+# ./msgpack.mingw.sh  # on msys
+# gem push msgpack-$version.gem
+# gem push msgpack-$version-x86-mingw32.gem
+# gem push msgpack-$version-mswin32.gem
+
diff --git a/ruby/msgpack.gemspec b/ruby/msgpack.gemspec
index 7273881c..4575c70c 100644
--- a/ruby/msgpack.gemspec
+++ b/ruby/msgpack.gemspec
@@ -1,5 +1,5 @@
 Gem::Specification.new do |s|
-	s.platform = Gem::Platform::RUBY
+  s.platform = Gem::Platform::RUBY
   s.name = "msgpack"
   s.version = "0.3.3"
   s.summary = "MessagePack, a binary-based efficient data interchange format."
@@ -7,10 +7,10 @@ Gem::Specification.new do |s|
   s.email = "frsyuki@users.sourceforge.jp"
   s.homepage = "http://msgpack.sourceforge.jp/"
   s.rubyforge_project = "msgpack"
-	s.has_rdoc = false
-	s.extra_rdoc_files = ["README", "ChangeLog", "AUTHORS"]
+  s.has_rdoc = false
+  s.extra_rdoc_files = ["README", "ChangeLog", "AUTHORS"]
   s.require_paths = ["lib", "ext"]
   s.files = Dir["lib/**/*", "ext/**/*", "msgpack/**/*", "test/**/*"]
-	s.test_files = Dir["test/test_*.rb"]
-	s.extensions = Dir["ext/**/extconf.rb"]
+  s.test_files = Dir["test/test_*.rb"]
+  s.extensions = Dir["ext/**/extconf.rb"]
 end
diff --git a/ruby/msgpack.mingw.gemspec b/ruby/msgpack.mingw.gemspec
new file mode 100644
index 00000000..3d2e7dc8
--- /dev/null
+++ b/ruby/msgpack.mingw.gemspec
@@ -0,0 +1,16 @@
+Gem::Specification.new do |s|
+  s.platform = Gem::Platform::CURRENT
+  s.name = "msgpack"
+  s.version = "0.3.3"
+  s.summary = "MessagePack, a binary-based efficient data interchange format."
+  s.author = "FURUHASHI Sadayuki"
+  s.email = "frsyuki@users.sourceforge.jp"
+  s.homepage = "http://msgpack.sourceforge.jp/"
+  s.rubyforge_project = "msgpack"
+  s.has_rdoc = false
+  s.extra_rdoc_files = ["README", "ChangeLog", "AUTHORS"]
+  s.require_paths = ["lib", "ext"]
+  s.files = Dir["lib/**/*", "ext/**/*", "msgpack/**/*", "test/**/*"]
+  s.test_files = Dir["test/test_*.rb"]
+  s.extensions = Dir["ext/**/extconf.rb"]
+end
diff --git a/ruby/msgpack.mingw.sh b/ruby/msgpack.mingw.sh
new file mode 100755
index 00000000..ec752349
--- /dev/null
+++ b/ruby/msgpack.mingw.sh
@@ -0,0 +1,21 @@
+#!/bin/sh
+if [ -z "$1" ];then
+	echo "usage: $0 <version>"
+	exit 1
+fi
+
+version=$1
+build=msgpack-mingw-build
+
+./makegem.sh
+gem build msgpack.mingw.gemspec
+rm -rf $build
+mkdir $build
+cd $build
+tar xvf ../msgpack-$version-x86-mingw32.gem
+gunzip metadata.gz
+sed s/x86-mingw32/mswin32/ metadata > metadata.tmp
+mv metadata.tmp metadata
+gzip metadata
+tar cvf msgpack-$version-mswin32.gem metadata.gz data.tar.gz
+