diff --git a/sensu-plugins-mailgun.gemspec b/sensu-plugins-mailgun.gemspec
index c7ec83b..7c62f22 100644
--- a/sensu-plugins-mailgun.gemspec
+++ b/sensu-plugins-mailgun.gemspec
@@ -32,7 +32,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'tz',                '0.0.1'
   s.add_runtime_dependency 'tzinfo',            '1.2.2'
 
-  s.add_development_dependency 'bundler',                   '~> 1.7'
+  s.add_development_dependency 'bundler',                   '~> 2.2'
   s.add_development_dependency 'codeclimate-test-reporter', '~> 0.4'
   s.add_development_dependency 'github-markup',             '~> 3.0'
   s.add_development_dependency 'pry',                       '~> 0.10'