diff --git a/lib/rb/thrift.gemspec b/lib/rb/thrift.gemspec
index 68bb4e1..17e1da2 100644
--- a/lib/rb/thrift.gemspec
+++ b/lib/rb/thrift.gemspec
@@ -26,7 +26,7 @@
 
   s.require_paths = %w[lib ext]
 
-  s.add_development_dependency 'bundler',            '>= 1.11'
+  s.add_development_dependency 'bundler',            '~> 2.1.4'
   s.add_development_dependency 'pry',                '~> 0.11.3'
   s.add_development_dependency 'pry-byebug',         '~> 3.6'
   s.add_development_dependency 'pry-stack_explorer', '~> 0.4.9.2'