diff --git a/Gemfile b/Gemfile
index 139d89e34..a6e07758b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,6 +9,6 @@ group :development, :test do
   gem "rubocop", "~> 1.7.0", require: false
   gem "simplecov", "~>0.21.2", require: false
   gem "test-unit", "~>3.3.7", require: false
-  gem "tomlrb"
+  gem "tomlrb", "2.0.1"
   gem "yard"
 end