diff --git a/Gemfile b/Gemfile
index c09e708..c56185e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,3 +20,5 @@ gem 'ruboty-slack'
 gem 'ruboty-syoboi_calendar'
 gem 'ruboty-talk'
 gem 'ruboty-wareki'
+
+gem 'nokogiri', '>= 1.6.7.1'
diff --git a/Gemfile.lock b/Gemfile.lock
index a8efe42..e06ea71 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -37,7 +37,7 @@ GEM
     multipart-post (2.0.0)
     natto (1.0.1)
       ffi (>= 1.9.0)
-    nokogiri (1.6.7)
+    nokogiri (1.6.7.1)
       mini_portile2 (~> 2.0.0.rc2)
     octokit (4.2.0)
       sawyer (~> 0.6.0, >= 0.5.3)
@@ -131,6 +131,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  nokogiri (>= 1.6.7.1)
   rake
   ruboty-aa
   ruboty-alias