diff --git a/logger.gemspec b/logger.gemspec
index d2c8512..c4bc0ac 100644
--- a/logger.gemspec
+++ b/logger.gemspec
@@ -15,7 +15,7 @@ Gem::Specification.new do |spec|
   spec.homepage      = "https://github.com/ruby/logger"
   spec.license       = "BSD-2-Clause"
 
-  spec.files         = ["Gemfile", "LICENSE.txt", "README.md", "Rakefile", "lib/logger.rb", "logger.gemspec"]
+  spec.files         = Dir.glob("lib/**/*.rb") + ["logger.gemspec"]
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]