diff --git a/lib/racc/racc.gemspec b/lib/racc/racc.gemspec
index cf98f93be2..810f9a76b9 100644
--- a/lib/racc/racc.gemspec
+++ b/lib/racc/racc.gemspec
@@ -45,59 +45,12 @@ DESC
     "sample/array.y", "sample/array2.y", "sample/calc-ja.y",
     "sample/calc.y", "sample/conflict.y", "sample/hash.y",
     "sample/lalr.y", "sample/lists.y", "sample/syntax.y",
-    "sample/yyerr.y",
-    "test/assets/cadenza.y", "test/assets/cast.y",
-    "test/assets/chk.y", "test/assets/conf.y",
-    "test/assets/csspool.y", "test/assets/digraph.y",
-    "test/assets/echk.y", "test/assets/edtf.y", "test/assets/err.y",
-    "test/assets/error_recovery.y", "test/assets/expect.y",
-    "test/assets/firstline.y", "test/assets/huia.y",
-    "test/assets/ichk.y", "test/assets/intp.y",
-    "test/assets/journey.y", "test/assets/liquor.y",
-    "test/assets/machete.y", "test/assets/macruby.y",
-    "test/assets/mailp.y", "test/assets/mediacloth.y",
-    "test/assets/mof.y", "test/assets/namae.y", "test/assets/nasl.y",
-    "test/assets/newsyn.y", "test/assets/noend.y",
-    "test/assets/nokogiri-css.y", "test/assets/nonass.y",
-    "test/assets/normal.y", "test/assets/norule.y",
-    "test/assets/nullbug1.y", "test/assets/nullbug2.y",
-    "test/assets/opal.y", "test/assets/opt.y",
-    "test/assets/percent.y", "test/assets/php_serialization.y",
-    "test/assets/recv.y", "test/assets/riml.y",
-    "test/assets/rrconf.y", "test/assets/ruby18.y",
-    "test/assets/ruby19.y", "test/assets/ruby20.y",
-    "test/assets/ruby21.y", "test/assets/ruby22.y",
-    "test/assets/scan.y", "test/assets/syntax.y",
-    "test/assets/tp_plus.y", "test/assets/twowaysql.y",
-    "test/assets/unterm.y", "test/assets/useless.y",
-    "test/assets/yyerr.y", "test/bench.y", "test/helper.rb",
-    "test/infini.y", "test/regress/cadenza", "test/regress/cast",
-    "test/regress/csspool", "test/regress/edtf", "test/regress/huia",
-    "test/regress/journey", "test/regress/liquor",
-    "test/regress/machete", "test/regress/mediacloth",
-    "test/regress/mof", "test/regress/namae", "test/regress/nasl",
-    "test/regress/nokogiri-css", "test/regress/opal",
-    "test/regress/php_serialization", "test/regress/riml",
-    "test/regress/ruby18", "test/regress/ruby22",
-    "test/regress/tp_plus", "test/regress/twowaysql",
-    "test/scandata/brace", "test/scandata/gvar",
-    "test/scandata/normal", "test/scandata/percent",
-    "test/scandata/slash", "test/src.intp", "test/start.y",
-    "test/test_chk_y.rb", "test/test_grammar_file_parser.rb",
-    "test/test_racc_command.rb", "test/test_scan_y.rb",
-    "test/testscanner.rb", "doc/en/racc.en.rhtml", "doc/ja/racc.ja.rhtml",
-    "doc/en/Overview-of-racc.md"
+    "sample/yyerr.y"
   ]
   s.require_paths = ["lib"]
   s.required_ruby_version = ">= 2.5"
   s.rdoc_options = ["--main", "README.rdoc"]
-  s.extra_rdoc_files = [
-    "README.ja.rdoc", "README.rdoc",
-    "rdoc/en/NEWS.en.rdoc", "rdoc/en/grammar.en.rdoc",
-    "rdoc/ja/NEWS.ja.rdoc", "rdoc/ja/debug.ja.rdoc",
-    "rdoc/ja/grammar.ja.rdoc", "rdoc/ja/parser.ja.rdoc",
-    "README.ja.rdoc", "README.rdoc"
-  ]
+  s.extra_rdoc_files = ["README.ja.rdoc", "README.rdoc"]
 
   if RUBY_PLATFORM =~ /java/
     s.files << 'lib/racc/cparse-jruby.jar'