diff --git a/.gitignore b/.gitignore
index 34d5138..b3d1b1b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,2 @@
-xkremap
-mruby/
-*.o
+/xkremap
+/mruby
diff --git a/Makefile b/Makefile
index 05044d6..84a64fb 100644
--- a/Makefile
+++ b/Makefile
@@ -6,12 +6,12 @@ OBJS=src/main.o
 
 all: xkremap
 
-xkremap: $(OBJS)
-	$(LD) $(OBJS) $(LDFLAGS) -o $@
+xkremap: mruby/build/host/bin/xkremap
+	cp mruby/build/host/bin/xkremap xkremap
 
 mruby:
 	curl -L --fail --retry 3 --retry-delay 1 https://github.com/mruby/mruby/archive/1.2.0.tar.gz -s -o - | tar zxf -
 	mv mruby-1.2.0 $@
 
-mruby/build/host/bin/mruby: mruby
+mruby/build/host/bin/xkremap: mruby build_config.rb tools/xkremap/xkremap.c
 	cd mruby && MRUBY_CONFIG="$(current_dir)/build_config.rb" make
diff --git a/build_config.rb b/build_config.rb
index 6b54359..d9a2f8e 100644
--- a/build_config.rb
+++ b/build_config.rb
@@ -1,138 +1,9 @@
 MRuby::Build.new do |conf|
-  # load specific toolchain settings
+  toolchain :gcc
 
-  # Gets set by the VS command prompts.
-  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
-    toolchain :visualcpp
-  else
-    toolchain :gcc
+  conf.gem File.expand_path(File.dirname(__FILE__))
+  conf.instance_eval do
+    # Allow showing backtrace.
+    @mrbc.compile_options += ' -g'
   end
-
-  enable_debug
-
-  # Use mrbgems
-  # conf.gem 'examples/mrbgems/ruby_extension_example'
-  # conf.gem 'examples/mrbgems/c_extension_example' do |g|
-  #   g.cc.flags << '-g' # append cflags in this gem
-  # end
-  # conf.gem 'examples/mrbgems/c_and_ruby_extension_example'
-  # conf.gem :github => 'masuidrive/mrbgems-example', :checksum_hash => '76518e8aecd131d047378448ac8055fa29d974a9'
-  # conf.gem :git => 'git@github.com:masuidrive/mrbgems-example.git', :branch => 'master', :options => '-v'
-
-  # include the default GEMs
-  conf.gembox 'default'
-  # C compiler settings
-  # conf.cc do |cc|
-  #   cc.command = ENV['CC'] || 'gcc'
-  #   cc.flags = [ENV['CFLAGS'] || %w()]
-  #   cc.include_paths = ["#{root}/include"]
-  #   cc.defines = %w(DISABLE_GEMS)
-  #   cc.option_include_path = '-I%s'
-  #   cc.option_define = '-D%s'
-  #   cc.compile_options = "%{flags} -MMD -o %{outfile} -c %{infile}"
-  # end
-
-  # mrbc settings
-  # conf.mrbc do |mrbc|
-  #   mrbc.compile_options = "-g -B%{funcname} -o-" # The -g option is required for line numbers
-  # end
-
-  # Linker settings
-  # conf.linker do |linker|
-  #   linker.command = ENV['LD'] || 'gcc'
-  #   linker.flags = [ENV['LDFLAGS'] || []]
-  #   linker.flags_before_libraries = []
-  #   linker.libraries = %w()
-  #   linker.flags_after_libraries = []
-  #   linker.library_paths = []
-  #   linker.option_library = '-l%s'
-  #   linker.option_library_path = '-L%s'
-  #   linker.link_options = "%{flags} -o %{outfile} %{objs} %{libs}"
-  # end
-
-  # Archiver settings
-  # conf.archiver do |archiver|
-  #   archiver.command = ENV['AR'] || 'ar'
-  #   archiver.archive_options = 'rs %{outfile} %{objs}'
-  # end
-
-  # Parser generator settings
-  # conf.yacc do |yacc|
-  #   yacc.command = ENV['YACC'] || 'bison'
-  #   yacc.compile_options = '-o %{outfile} %{infile}'
-  # end
-
-  # gperf settings
-  # conf.gperf do |gperf|
-  #   gperf.command = 'gperf'
-  #   gperf.compile_options = '-L ANSI-C -C -p -j1 -i 1 -g -o -t -N mrb_reserved_word -k"1,3,$" %{infile} > %{outfile}'
-  # end
-
-  # file extensions
-  # conf.exts do |exts|
-  #   exts.object = '.o'
-  #   exts.executable = '' # '.exe' if Windows
-  #   exts.library = '.a'
-  # end
-
-  # file separetor
-  # conf.file_separator = '/'
-
-  # bintest
-  # conf.enable_bintest
-end
-
-MRuby::Build.new('host-debug') do |conf|
-  # load specific toolchain settings
-
-  # Gets set by the VS command prompts.
-  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
-    toolchain :visualcpp
-  else
-    toolchain :gcc
-  end
-
-  enable_debug
-
-  # include the default GEMs
-  conf.gembox 'default'
-
-  # C compiler settings
-  conf.cc.defines = %w(MRB_ENABLE_DEBUG_HOOK)
-
-  # Generate mruby debugger command (require mruby-eval)
-  conf.gem :core => "mruby-bin-debugger"
-
-  # bintest
-  # conf.enable_bintest
 end
-
-MRuby::Build.new('test') do |conf|
-  # Gets set by the VS command prompts.
-  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
-    toolchain :visualcpp
-  else
-    toolchain :gcc
-  end
-
-  enable_debug
-  conf.enable_bintest
-  conf.enable_test
-
-  conf.gembox 'default'
-end
-
-# Define cross build settings
-# MRuby::CrossBuild.new('32bit') do |conf|
-#   toolchain :gcc
-#
-#   conf.cc.flags << "-m32"
-#   conf.linker.flags << "-m32"
-#
-#   conf.build_mrbtest_lib_only
-#
-#   conf.gem 'examples/mrbgems/c_and_ruby_extension_example'
-#
-#   conf.test_runner.command = 'env'
-#
-# end
diff --git a/mrbgem.rake b/mrbgem.rake
new file mode 100644
index 0000000..a82b4c7
--- /dev/null
+++ b/mrbgem.rake
@@ -0,0 +1,6 @@
+MRuby::Gem::Specification.new('xkremap') do |spec|
+  spec.license = 'MIT'
+  spec.author  = 'Takashi Kokubun'
+  spec.summary = 'Dynamic key remapper for X Window System'
+  spec.bins    = ['xkremap']
+end
diff --git a/tools/xkremap/xkremap.c b/tools/xkremap/xkremap.c
new file mode 100644
index 0000000..27f4618
--- /dev/null
+++ b/tools/xkremap/xkremap.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int
+main(void)
+{
+  printf("Hello xkremap!\n");
+  return 0;
+}