diff --git a/Gemfile b/Gemfile
index 20c64be..0361fa0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem "rexml"
 gem "webrick"
 gem "RedCloth", ">=4.0.0"
 gem "erubis"
-gem "nokogiri", '~>1.8.0'
+gem "nokogiri", '~>1.13.6'
 gem "rake", '~>12.3.2'
 gem "rdoc"
 gem "json", "~> 2.5.1"
diff --git a/Gemfile.lock b/Gemfile.lock
index bdc3748..be7903f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -34,11 +34,11 @@ GEM
     iconv (1.0.8)
     json (2.5.1)
     kgio (2.11.4)
-    mini_portile2 (2.3.0)
     mysql2 (0.5.4)
-    nokogiri (1.8.5)
-      mini_portile2 (~> 2.3.0)
+    nokogiri (1.13.6-x86_64-linux)
+      racc (~> 1.4)
     power_assert (2.0.1)
+    racc (1.6.0)
     rack (2.2.4)
     rails_xss (0.4.0)
     raindrops (0.20.0)
@@ -73,7 +73,7 @@ DEPENDENCIES
   json (~> 2.5.1)
   maruku!
   mysql2
-  nokogiri (~> 1.8.0)
+  nokogiri (~> 1.13.6)
   rack (>= 2.0)
   rails_xss (~> 0.4.0)
   rake (~> 12.3.2)