diff --git a/Gemfile b/Gemfile
index f11cf99..71f8b81 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,6 @@
 source 'https://rubygems.org'
 
+gem "base64"
 gem "rspec"
 gem "rake"
 gem "simplecov", "~> 0.15.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index 952c30c..358a526 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,6 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    base64 (0.2.0)
     diff-lcs (1.5.1)
     docile (1.1.5)
     json (2.7.1)
@@ -37,6 +38,7 @@ PLATFORMS
   x86-mingw32
 
 DEPENDENCIES
+  base64
   json
   rake
   rdoc