diff --git a/Rakefile b/Rakefile
index bd93b47..85e8551 100644
--- a/Rakefile
+++ b/Rakefile
@@ -16,7 +16,6 @@ mruby_config=File.expand_path(ENV["MRUBY_CONFIG"] || "build_config.rb")
 ENV['MRUBY_ROOT'] = mruby_root
 ENV['MRUBY_CONFIG'] = mruby_config
 Rake::Task[:mruby].invoke unless Dir.exist?(mruby_root)
-Dir.chdir(mruby_root)
 load "#{mruby_root}/Rakefile"
 
 load File.join(File.expand_path(File.dirname(__FILE__)), "mrbgem.rake")
@@ -27,12 +26,14 @@ APP_VERSION = (app_version.nil? || app_version.empty?) ? "unknown" : app_version
 
 desc "compile all the binaries"
 task :compile => [:all] do
-  MRuby.each_target do |target|
-    `#{target.cc.command} --version`
-    abort("Command #{target.cc.command} for #{target.name} is missing.") unless $?.success?
-  end
-  %W(#{mruby_root}/build/x86_64-pc-linux-gnu/bin/#{APP_NAME} #{mruby_root}/build/i686-pc-linux-gnu/#{APP_NAME}").each do |bin|
-    sh "strip --strip-unneeded #{bin}" if File.exist?(bin)
+  Dir.chdir(mruby_root) do
+    MRuby.each_target do |target|
+      `#{target.cc.command} --version`
+      abort("Command #{target.cc.command} for #{target.name} is missing.") unless $?.success?
+    end
+    %W(#{mruby_root}/build/x86_64-pc-linux-gnu/bin/#{APP_NAME} #{mruby_root}/build/i686-pc-linux-gnu/#{APP_NAME}).each do |bin|
+      sh "strip --strip-unneeded #{bin}" if File.exist?(bin)
+    end
   end
 end
 
@@ -40,12 +41,14 @@ namespace :test do
   desc "run mruby & unit tests"
   # only build mtest for host
   task :mtest => :compile do
-    # in order to get mruby/test/t/synatx.rb __FILE__ to pass,
-    # we need to make sure the tests are built relative from mruby_root
-    MRuby.each_target do |target|
-      # only run unit tests here
-      target.enable_bintest = false
-      run_test if target.test_enabled?
+    Dir.chdir(mruby_root) do
+      # in order to get mruby/test/t/synatx.rb __FILE__ to pass,
+      # we need to make sure the tests are built relative from mruby_root
+      MRuby.each_target do |target|
+        # only run unit tests here
+        target.enable_bintest = false
+        run_test if target.test_enabled?
+      end
     end
   end
 
@@ -63,9 +66,11 @@ namespace :test do
 
   desc "run integration tests"
   task :bintest => :compile do
-    MRuby.each_target do |target|
-      clean_env(%w(MRUBY_ROOT MRUBY_CONFIG)) do
-        run_bintest if target.bintest_enabled?
+    Dir.chdir(mruby_root) do
+      MRuby.each_target do |target|
+        clean_env(%w(MRUBY_ROOT MRUBY_CONFIG)) do
+          run_bintest if target.bintest_enabled?
+        end
       end
     end
   end
@@ -77,38 +82,42 @@ task :test => ['test:bintest', 'test:mtest']
 
 desc "cleanup"
 task :clean do
-  sh "rake deep_clean"
+  Dir.chdir(mruby_root) do
+    sh "rake deep_clean"
+  end
 end
 
 desc "generate a release tarball"
 task :release => :compile do
   require 'tmpdir'
 
-  # since we're in the mruby/
-  release_dir  = "releases/v#{APP_VERSION}"
-  release_path = Dir.pwd + "/../#{release_dir}"
-  app_name     = "#{APP_NAME}-#{APP_VERSION}"
-  FileUtils.mkdir_p(release_path)
-
-  Dir.mktmpdir do |tmp_dir|
-    Dir.chdir(tmp_dir) do
-      MRuby.each_target do |target|
-        next if name == "host"
-
-        arch = name
-        bin  = "#{build_dir}/bin/#{exefile(APP_NAME)}"
-        FileUtils.mkdir_p(name)
-        FileUtils.cp(bin, name)
-
-        Dir.chdir(arch) do
-          arch_release = "#{app_name}-#{arch}"
-          puts "Writing #{release_dir}/#{arch_release}.tgz"
-          `tar czf #{release_path}/#{arch_release}.tgz *`
+  Dir.chdir(mruby_root) do
+    # since we're in the mruby/
+    release_dir  = "releases/v#{APP_VERSION}"
+    release_path = Dir.pwd + "/../#{release_dir}"
+    app_name     = "#{APP_NAME}-#{APP_VERSION}"
+    FileUtils.mkdir_p(release_path)
+
+    Dir.mktmpdir do |tmp_dir|
+      Dir.chdir(tmp_dir) do
+        MRuby.each_target do |target|
+          next if name == "host"
+
+          arch = name
+          bin  = "#{build_dir}/bin/#{exefile(APP_NAME)}"
+          FileUtils.mkdir_p(name)
+          FileUtils.cp(bin, name)
+
+          Dir.chdir(arch) do
+            arch_release = "#{app_name}-#{arch}"
+            puts "Writing #{release_dir}/#{arch_release}.tgz"
+            `tar czf #{release_path}/#{arch_release}.tgz *`
+          end
         end
-      end
 
-      puts "Writing #{release_dir}/#{app_name}.tgz"
-      `tar czf #{release_path}/#{app_name}.tgz *`
+        puts "Writing #{release_dir}/#{app_name}.tgz"
+        `tar czf #{release_path}/#{app_name}.tgz *`
+      end
     end
   end
 end
diff --git a/mrblib/mruby-cli/setup.rb b/mrblib/mruby-cli/setup.rb
index b83cbb8..ad8ae36 100644
--- a/mrblib/mruby-cli/setup.rb
+++ b/mrblib/mruby-cli/setup.rb
@@ -330,10 +330,8 @@ def rakefile
 ENV['MRUBY_ROOT'] = mruby_root
 ENV['MRUBY_CONFIG'] = mruby_config
 Rake::Task[:mruby].invoke unless Dir.exist?(mruby_root)
-Dir.chdir(mruby_root)
 load "\#{mruby_root}/Rakefile"
 
-
 load File.join(File.expand_path(File.dirname(__FILE__)), "mrbgem.rake")
 
 current_gem = MRuby::Gem.current
@@ -342,13 +340,14 @@ def rakefile
 
 desc "compile binary"
 task :compile => [:all] do
-
-  MRuby.each_target do |target|
-    `\#{target.cc.command} --version`
-    abort("Command \#{target.cc.command} for \#{target.name} is missing.") unless $?.success?
-  end
-  %W(\#{mruby_root}/build/x86_64-pc-linux-gnu/bin/\#{APP_NAME} \#{mruby_root}/build/i686-pc-linux-gnu/\#{APP_NAME}).each do |bin|
-    sh "strip --strip-unneeded \#{bin}" if File.exist?(bin)
+  Dir.chdir(mruby_root) do
+    MRuby.each_target do |target|
+      `\#{target.cc.command} --version`
+      abort("Command \#{target.cc.command} for \#{target.name} is missing.") unless $?.success?
+    end
+    %W(\#{mruby_root}/build/x86_64-pc-linux-gnu/bin/\#{APP_NAME} \#{mruby_root}/build/i686-pc-linux-gnu/\#{APP_NAME}).each do |bin|
+      sh "strip --strip-unneeded \#{bin}" if File.exist?(bin)
+    end
   end
 end
 
@@ -356,12 +355,14 @@ def rakefile
   desc "run mruby & unit tests"
   # only build mtest for host
   task :mtest => :compile do
-    # in order to get mruby/test/t/synatx.rb __FILE__ to pass,
-    # we need to make sure the tests are built relative from mruby_root
-    MRuby.each_target do |target|
-      # only run unit tests here
-      target.enable_bintest = false
-      run_test if target.test_enabled?
+    Dir.chdir(mruby_root) do
+      # in order to get mruby/test/t/synatx.rb __FILE__ to pass,
+      # we need to make sure the tests are built relative from mruby_root
+      MRuby.each_target do |target|
+        # only run unit tests here
+        target.enable_bintest = false
+        run_test if target.test_enabled?
+      end
     end
   end
 
@@ -379,9 +380,11 @@ def clean_env(envs)
 
   desc "run integration tests"
   task :bintest => :compile do
-    MRuby.each_target do |target|
-      clean_env(%w(MRUBY_ROOT MRUBY_CONFIG)) do
-        run_bintest if target.bintest_enabled?
+    Dir.chdir(mruby_root) do
+      MRuby.each_target do |target|
+        clean_env(%w(MRUBY_ROOT MRUBY_CONFIG)) do
+          run_bintest if target.bintest_enabled?
+        end
       end
     end
   end
@@ -393,38 +396,42 @@ def clean_env(envs)
 
 desc "cleanup"
 task :clean do
-  sh "rake deep_clean"
+  Dir.chdir(mruby_root) do
+    sh "rake deep_clean"
+  end
 end
 
 desc "generate a release tarball"
 task :release => :compile do
   require 'tmpdir'
 
-  # since we're in the mruby/
-  release_dir  = "releases/v\#{APP_VERSION}"
-  release_path = Dir.pwd + "/../\#{release_dir}"
-  app_name     = "\#{APP_NAME}-\#{APP_VERSION}"
-  FileUtils.mkdir_p(release_path)
-
-  Dir.mktmpdir do |tmp_dir|
-    Dir.chdir(tmp_dir) do
-      MRuby.each_target do |target|
-        next if name == "host"
-
-        arch = name
-        bin  = "\#{build_dir}/bin/\#{exefile(APP_NAME)}"
-        FileUtils.mkdir_p(name)
-        FileUtils.cp(bin, name)
-
-        Dir.chdir(arch) do
-          arch_release = "\#{app_name}-\#{arch}"
-          puts "Writing \#{release_dir}/\#{arch_release}.tgz"
-          `tar czf \#{release_path}/\#{arch_release}.tgz *`
+  Dir.chdir(mruby_root) do
+    # since we're in the mruby/
+    release_dir  = "releases/v\#{APP_VERSION}"
+    release_path = Dir.pwd + "/../\#{release_dir}"
+    app_name     = "\#{APP_NAME}-\#{APP_VERSION}"
+    FileUtils.mkdir_p(release_path)
+
+    Dir.mktmpdir do |tmp_dir|
+      Dir.chdir(tmp_dir) do
+        MRuby.each_target do |target|
+          next if name == "host"
+
+          arch = name
+          bin  = "\#{build_dir}/bin/\#{exefile(APP_NAME)}"
+          FileUtils.mkdir_p(name)
+          FileUtils.cp(bin, name)
+
+          Dir.chdir(arch) do
+            arch_release = "\#{app_name}-\#{arch}"
+            puts "Writing \#{release_dir}/\#{arch_release}.tgz"
+            `tar czf \#{release_path}/\#{arch_release}.tgz *`
+          end
         end
-      end
 
-      puts "Writing \#{release_dir}/\#{app_name}.tgz"
-      `tar czf \#{release_path}/\#{app_name}.tgz *`
+        puts "Writing \#{release_dir}/\#{app_name}.tgz"
+        `tar czf \#{release_path}/\#{app_name}.tgz *`
+      end
     end
   end
 end