diff --git a/net-smtp.gemspec b/net-smtp.gemspec
index bd0a2dd..3c21042 100644
--- a/net-smtp.gemspec
+++ b/net-smtp.gemspec
@@ -22,9 +22,11 @@ Gem::Specification.new do |spec|
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage
 
-  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
-    `git ls-files -z 2>/dev/null`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
-  end
+  spec.files         = %w[
+    LICENSE.txt
+    lib/net/smtp.rb
+    net-smtp.gemspec
+  ]
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]