diff --git a/Gemfile b/Gemfile
index e4b9b27..acaf874 100644
--- a/Gemfile
+++ b/Gemfile
@@ -34,7 +34,7 @@ gem 'turbolinks', '~> 5.2.1'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 gem 'jbuilder', '~> 2.11.2'
 # bundle exec rake doc:rails generates the API under doc/api.
-gem 'sdoc', '~> 2.1.0',          group: :doc
+gem 'sdoc', '~> 2.2.0',          group: :doc
 
 gem 'web-console', '~> 4.1.0', group: :development
 gem 'listen', '~> 3.5.1', group: :development
diff --git a/Gemfile.lock b/Gemfile.lock
index 7346180..a2e37e7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -225,7 +225,7 @@ GEM
       sprockets (> 3.0)
       sprockets-rails
       tilt
-    sdoc (2.1.0)
+    sdoc (2.2.0)
       rdoc (>= 5.0)
     sprockets (4.0.2)
       concurrent-ruby (~> 1.0)
@@ -287,7 +287,7 @@ DEPENDENCIES
   rails-controller-testing
   rails-i18n (~> 6.0.0)
   sassc-rails (~> 2.1.2)
-  sdoc (~> 2.1.0)
+  sdoc (~> 2.2.0)
   sqlite3 (~> 1.4.1)
   turbolinks (~> 5.2.1)
   tzinfo-data