diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b4bb41..9f7604e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Development
 
+* Exclude spec files from the gem package to lighten the package size.
+
 ## v3.0.0
 
 * Check whether rspec-rails is used in the target project via `Gemfile.lock` when `-s/--skip-dynamic-analysis` option is specified. ([#88](https://github.com/yujinakayama/transpec/issues/88))
diff --git a/transpec.gemspec b/transpec.gemspec
index 61e36a4..e7c568d 100644
--- a/transpec.gemspec
+++ b/transpec.gemspec
@@ -15,9 +15,8 @@ Gem::Specification.new do |spec|
   spec.homepage      = 'http://yujinakayama.me/transpec/'
   spec.license       = 'MIT'
 
-  spec.files         = `git ls-files`.split($/)
+  spec.files         = `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
-  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ['lib']
 
   spec.required_ruby_version = '>= 1.9.3'