diff --git a/Gemfile b/Gemfile
index a588d17..7e2d83c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,10 +1,10 @@
 source 'https://rubygems.org'
-gem "i18n",      "~> 0.7", ">= 0.7.0"
-gem "gpgme",     "~> 2.0", ">= 2.0.12"
-gem "highline",  "~> 1.7", ">= 1.7.8"
-gem "locale",    "~> 2.1", ">= 2.1.2"
-gem "colorize",  "~> 0.8", ">= 0.8.1"
-gem "net-ssh",   "~> 3.2", ">= 3.2.0"
-gem "net-sftp",  "~> 2.1", ">= 2.1.2"
-gem "clipboard", "~> 1.1", ">= 1.1.1"
-gem "rotp",      "~> 3.1", ">= 3.1.0"
+gem 'clipboard', '~> 1.1', '>= 1.1.1'
+gem 'colorize',  '~> 0.8', '>= 0.8.1'
+gem 'gpgme',     '~> 2.0', '>= 2.0.12'
+gem 'highline',  '~> 1.7', '>= 1.7.8'
+gem 'i18n',      '~> 0.7', '>= 0.7.0'
+gem 'locale',    '~> 2.1', '>= 2.1.2'
+gem 'net-sftp',  '~> 2.1', '>= 2.1.2'
+gem 'net-ssh',   '~> 3.2', '>= 3.2.0'
+gem 'rotp',      '~> 3.1', '>= 3.1.0'
diff --git a/mpw.gemspec b/mpw.gemspec
index 80d9344..7f687ab 100644
--- a/mpw.gemspec
+++ b/mpw.gemspec
@@ -1,4 +1,5 @@
 # coding: utf-8
+
 lib = File.expand_path('../lib', __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 
@@ -12,18 +13,18 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'https://github.com/nishiki/manage-password'
   spec.license       = 'GPL-2.0'
 
-  spec.files         = `git ls-files -z`.split("\x0")
+  spec.files         = %x(git ls-files -z).split("\x0")
   spec.executables   = ['mpw']
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ['lib']
 
-  spec.add_dependency "i18n",      "~> 0.7", ">= 0.7.0"
-  spec.add_dependency "gpgme",     "~> 2.0", ">= 2.0.12"
-  spec.add_dependency "highline",  "~> 1.7", ">= 1.7.8"
-  spec.add_dependency "locale",    "~> 2.1", ">= 2.1.2"
-  spec.add_dependency "colorize",  "~> 0.8", ">= 0.8.1"
-  spec.add_dependency "net-ssh",   "~> 3.2", ">= 3.2.0"
-  spec.add_dependency "net-sftp",  "~> 2.1", ">= 2.1.2"
-  spec.add_dependency "clipboard", "~> 1.1", ">= 1.1.1"
-  spec.add_dependency "rotp",      "~> 3.1", ">= 3.1.0"
+  spec.add_dependency 'i18n',      '~> 0.7', '>= 0.7.0'
+  spec.add_dependency 'gpgme',     '~> 2.0', '>= 2.0.12'
+  spec.add_dependency 'highline',  '~> 1.7', '>= 1.7.8'
+  spec.add_dependency 'locale',    '~> 2.1', '>= 2.1.2'
+  spec.add_dependency 'colorize',  '~> 0.8', '>= 0.8.1'
+  spec.add_dependency 'net-ssh',   '~> 3.2', '>= 3.2.0'
+  spec.add_dependency 'net-sftp',  '~> 2.1', '>= 2.1.2'
+  spec.add_dependency 'clipboard', '~> 1.1', '>= 1.1.1'
+  spec.add_dependency 'rotp',      '~> 3.1', '>= 3.1.0'
 end