diff --git a/tc_validator.gemspec b/tc_validator.gemspec
index 05beca9..e2e53e9 100644
--- a/tc_validator.gemspec
+++ b/tc_validator.gemspec
@@ -20,7 +20,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_development_dependency "bundler", "~> 1.9"
+  spec.add_development_dependency "bundler", "~> 2.1"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "activesupport"
   spec.add_development_dependency "rspec"