--- a/zabbix_sender.gemspec
+++ b/zabbix_sender.gemspec
@@ -12,7 +12,7 @@
   spec.summary       = %q{Zabbix Sender gem}
   spec.homepage      = "https://github.com/nownabe/zabbix_sender"
 
-  spec.files         = `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  spec.files         = Dir["lib/**/*"]
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]