diff --git a/ext/date/date.gemspec b/ext/date/date.gemspec
index f118456810..cb439bd0a5 100644
--- a/ext/date/date.gemspec
+++ b/ext/date/date.gemspec
@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
     s.require_path = %w{lib}
 
     s.files = [
-      "README.md",
+      "README.md", "COPYING", "BSDL",
       "lib/date.rb", "ext/date/date_core.c", "ext/date/date_parse.c", "ext/date/date_strftime.c",
       "ext/date/date_strptime.c", "ext/date/date_tmx.h", "ext/date/extconf.rb", "ext/date/prereq.mk",
       "ext/date/zonetab.h", "ext/date/zonetab.list"