diff --git a/gemfiles/Gemfile.rails-6.1.x b/gemfiles/Gemfile.rails-6.1.x
index 6f67f785..104487c1 100644
--- a/gemfiles/Gemfile.rails-6.1.x
+++ b/gemfiles/Gemfile.rails-6.1.x
@@ -8,6 +8,7 @@ gem 'test_declarative', '0.0.6'
 gem 'rake'
 gem 'minitest', '~> 5.14'
 gem 'racc'
+gem 'base64'
 
 platforms :mri do
   gem 'oj'