diff --git a/docs/Gemfile b/docs/Gemfile
index 27acded18..db31c828b 100644
--- a/docs/Gemfile
+++ b/docs/Gemfile
@@ -7,3 +7,8 @@ end
 group :development do
   gem "webrick"
 end
+
+# used to be in standard library
+gem "csv"
+gem "base64"
+gem "bigdecimal"
diff --git a/docs/Gemfile.lock b/docs/Gemfile.lock
index 9e014a8bd..9416df0df 100644
--- a/docs/Gemfile.lock
+++ b/docs/Gemfile.lock
@@ -8,6 +8,8 @@ GEM
       tzinfo (~> 2.0)
     addressable (2.8.1)
       public_suffix (>= 2.0.2, < 6.0)
+    base64 (0.3.0)
+    bigdecimal (4.0.1)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
@@ -15,6 +17,7 @@ GEM
     colorator (1.1.0)
     commonmarker (0.23.10)
     concurrent-ruby (1.2.2)
+    csv (3.3.5)
     dnsruby (1.61.9)
       simpleidn (~> 0.1)
     em-websocket (0.5.3)
@@ -266,6 +269,9 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  base64
+  bigdecimal
+  csv
   github-pages
   webrick