diff --git a/nkf.gemspec b/nkf.gemspec
index bd4e83d..1d4656d 100644
--- a/nkf.gemspec
+++ b/nkf.gemspec
@@ -27,7 +27,7 @@ Gem::Specification.new do |spec|
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
-    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features|bin|.github|test_sig)/}) }
   end
 
   if Gem::Platform === spec.platform and spec.platform =~ 'java' or RUBY_ENGINE == 'jruby'