diff --git a/fluentd.gemspec b/fluentd.gemspec
index 25ca1970c5..a5b5c805e3 100644
--- a/fluentd.gemspec
+++ b/fluentd.gemspec
@@ -24,7 +24,7 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency("cool.io", [">= 1.4.5", "< 2.0.0"])
   gem.add_runtime_dependency("serverengine", [">= 2.3.2", "< 3.0.0"])
   gem.add_runtime_dependency("http_parser.rb", [">= 0.5.1", "< 0.9.0"])
-  gem.add_runtime_dependency("sigdump", ["~> 0.2.2"])
+  gem.add_runtime_dependency("sigdump", ["~> 0.2.5"])
   gem.add_runtime_dependency("tzinfo", [">= 1.0", "< 3.0"])
   gem.add_runtime_dependency("tzinfo-data", ["~> 1.0"])
   gem.add_runtime_dependency("strptime", [">= 0.2.4", "< 1.0.0"])