diff --git a/act-fluent-logger-rails.gemspec b/act-fluent-logger-rails.gemspec
index 55c15f5..0f0cb31 100644
--- a/act-fluent-logger-rails.gemspec
+++ b/act-fluent-logger-rails.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.require_paths = ["lib"]
 
-  gem.add_development_dependency "rspec", '~> 3.5.0'
+  gem.add_development_dependency "rspec", '~> 3.8.0'
   gem.add_runtime_dependency "fluent-logger"
   gem.add_runtime_dependency "railties", ">= 4", "< 5.3"
   gem.add_runtime_dependency "activesupport", ">= 4", "< 5.3"