diff --git a/Gemfile b/Gemfile
index b22bf5a8..8aa1fda4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem 'faraday', '~> 0.9.2', :platforms => [:jruby_18, :ruby_18]
 gem 'jwt', '< 1.5.2', :platforms => [:jruby_18, :ruby_18]
 gem 'rake', '< 11.0'
-gem 'rdoc'
+gem 'rdoc', '~> 4.2.2'
 
 group :development do
   gem 'pry'