diff --git a/Gemfile b/Gemfile
index 15529c5..661a300 100644
--- a/Gemfile
+++ b/Gemfile
@@ -26,5 +26,5 @@ group :development do
   gem 'rspec', '~> 3.11'
   gem 'simplecov', '~> 0.21.2'
   gem 'timecop', '~> 0.9.5'
-  gem 'yard', '~> 0.9.27'
+  gem 'yard', '~> 0.9.28'
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index de97230..67030cb 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -103,7 +103,7 @@ GEM
       kgio (~> 2.6)
       raindrops (~> 0.7)
     webrick (1.7.0)
-    yard (0.9.27)
+    yard (0.9.28)
       webrick (~> 1.7.0)
 
 PLATFORMS
@@ -130,7 +130,7 @@ DEPENDENCIES
   thin (~> 1.8)
   timecop (~> 0.9.5)
   unicorn (~> 5.7)
-  yard (~> 0.9.27)
+  yard (~> 0.9.28)
 
 RUBY VERSION
    ruby 2.6.5p114