--- a/test-unit.gemspec
+++ b/test-unit.gemspec
@@ -24,11 +24,7 @@
   description = clean_white_space.call(entries[entries.index("Description") + 1])
   spec.summary, spec.description, = description.split(/\n\n+/, 3)
   spec.licenses = ["Ruby", "BSDL", "PSFL"] # lib/test/unit/diff.rb is PSFL
-  spec.files = ["README.md", "Rakefile"]
-  spec.files += ["COPYING", "BSDL", "PSFL"]
-  spec.files += Dir.glob("{lib,sample}/**/*.rb")
-  spec.files += Dir.glob("doc/text/**/*.*")
-  spec.test_files += Dir.glob("test/**/*")
+  spec.files += Dir.glob("lib/**/*.rb")
 
   spec.metadata = {
     "source_code_uri" => "https://github.com/test-unit/test-unit"