diff --git a/gemfiles/rails_6_0.gemfile b/gemfiles/rails_6_0.gemfile
index 9bc0085..821d401 100644
--- a/gemfiles/rails_6_0.gemfile
+++ b/gemfiles/rails_6_0.gemfile
@@ -6,5 +6,6 @@ gem "rake"
 gem "mocha", require: false
 gem "appraisal"
 gem "rails", "~> 6.0.0"
+gem "base64"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_6_1.gemfile b/gemfiles/rails_6_1.gemfile
index d285626..893032a 100644
--- a/gemfiles/rails_6_1.gemfile
+++ b/gemfiles/rails_6_1.gemfile
@@ -6,5 +6,6 @@ gem "rake"
 gem "mocha", require: false
 gem "appraisal"
 gem "rails", "~> 6.1.0"
+gem "base64"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_7_0.gemfile b/gemfiles/rails_7_0.gemfile
index 7c10193..bf6c376 100644
--- a/gemfiles/rails_7_0.gemfile
+++ b/gemfiles/rails_7_0.gemfile
@@ -6,5 +6,6 @@ gem "rake"
 gem "mocha", require: false
 gem "appraisal"
 gem "rails", "~> 7.0.0"
+gem "base64"
 
 gemspec path: "../"