diff --git a/mailinator.gemspec b/mailinator.gemspec
index c30e705..b0a3812 100644
--- a/mailinator.gemspec
+++ b/mailinator.gemspec
@@ -20,6 +20,6 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency 'hashie', '>= 3.5.4', '< 3.7.0'
 
-  spec.add_development_dependency 'bundler', '~> 1.16.2'
+  spec.add_development_dependency 'bundler', '~> 2.2.25'
   spec.add_development_dependency 'rake', '~> 12.3.1'
 end