diff --git a/Gemfile b/Gemfile
index 8a49b347..e7033c55 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,5 +9,5 @@ gem 'pandoc-ruby', '~> 2.0'
 gem 'middleman-data_source', '~> 0.8.1'
 gem 'rspec'
 gem 'rspec-xsd'
-gem 'nokogiri', '~> 1.10'
+gem 'nokogiri', '~> 1.13'
 gem 'html-proofer', '~> 3.7', '>= 3.7.6'
diff --git a/Gemfile.lock b/Gemfile.lock
index 6a8b2754..2b34bed7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -104,10 +104,11 @@ GEM
       em-websocket (~> 0.5.1)
       middleman-core (>= 3.3)
       rack-livereload (~> 0.3.15)
-    mini_portile2 (2.4.0)
+    mini_portile2 (2.8.0)
     minitest (5.14.2)
-    nokogiri (1.10.10)
-      mini_portile2 (~> 2.4.0)
+    nokogiri (1.13.9)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
     nokogumbo (2.0.2)
       nokogiri (~> 1.8, >= 1.8.4)
     padrino-helpers (0.13.3.4)
@@ -119,6 +120,7 @@ GEM
     pandoc-ruby (2.1.4)
     parallel (1.20.0)
     public_suffix (4.0.6)
+    racc (1.6.0)
     rack (2.2.3)
     rack-livereload (0.3.17)
       rack
@@ -166,7 +168,7 @@ DEPENDENCIES
   middleman-data_source (~> 0.8.1)
   middleman-dotenv (~> 2.0)
   middleman-livereload
-  nokogiri (~> 1.10)
+  nokogiri (~> 1.13)
   pandoc-ruby (~> 2.0)
   rspec
   rspec-xsd