diff --git a/Gemfile b/Gemfile
index de133667b..3156631f5 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,7 +13,7 @@ group :development do
 end
 
 group :testing do
-  gem 'html-proofer'
+  gem 'html-proofer', "~> 3.0"
   gem 'mdl'
   gem 'json-schema'
   gem 'toml'
diff --git a/Gemfile.lock b/Gemfile.lock
index c501d4ade..87634de77 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -13,11 +13,11 @@ GEM
     eventmachine (1.2.7)
     ffi (1.11.3)
     forwardable-extended (2.6.0)
-    html-proofer (3.15.0)
+    html-proofer (3.19.4)
       addressable (~> 2.3)
       mercenary (~> 0.3)
-      nokogumbo (~> 2.0)
-      parallel (~> 1.3)
+      nokogiri (~> 1.13)
+      parallel (~> 1.10)
       rainbow (~> 3.0)
       typhoeus (~> 1.3)
       yell (~> 2.0)
@@ -59,7 +59,7 @@ GEM
       mixlib-cli (~> 2.1, >= 2.1.1)
       mixlib-config (~> 2.2, >= 2.2.1)
     mercenary (0.3.6)
-    mini_portile2 (2.4.0)
+    mini_portile2 (2.8.8)
     minima (2.5.0)
       jekyll (~> 3.5)
       jekyll-feed (~> 0.9)
@@ -67,16 +67,16 @@ GEM
     mixlib-cli (2.1.1)
     mixlib-config (2.2.18)
       tomlrb
-    nokogiri (1.10.7)
-      mini_portile2 (~> 2.4.0)
-    nokogumbo (2.0.2)
-      nokogiri (~> 1.8, >= 1.8.4)
-    parallel (1.19.1)
+    nokogiri (1.13.10)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
+    parallel (1.24.0)
     parslet (1.8.2)
     pathutil (0.16.1)
       forwardable-extended (~> 2.6)
     public_suffix (4.0.1)
-    rainbow (3.0.0)
+    racc (1.8.1)
+    rainbow (3.1.1)
     rb-fsevent (0.10.3)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)
@@ -90,15 +90,15 @@ GEM
     toml (0.2.0)
       parslet (~> 1.8.0)
     tomlrb (1.2.9)
-    typhoeus (1.3.1)
+    typhoeus (1.4.1)
       ethon (>= 0.9.0)
-    yell (2.2.0)
+    yell (2.2.2)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  html-proofer
+  html-proofer (~> 3.0)
   jekyll
   jekyll-redirect-from
   json-schema