diff --git a/Gemfile b/Gemfile
index d519345..1f59542 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,3 +4,4 @@ gem 'octopress', '~> 3.0.0.rc.15'
 gem 'narray', :git => "https://github.com/tonyarnold/narray"
 gem 'gsl', :git => "https://github.com/tonyarnold/rb-gsl"
 
+gem 'html-proofer'
diff --git a/Gemfile.lock b/Gemfile.lock
index 8dcf063..63e25d0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -24,10 +24,20 @@ GEM
       execjs
     coffee-script-source (1.8.0)
     colorator (0.1)
+    colored (1.2)
+    ethon (0.7.1)
+      ffi (>= 1.3.0)
     execjs (2.2.1)
     fast-stemmer (1.0.2)
     ffi (1.9.5)
     hitimes (1.2.2)
+    html-proofer (1.4.0)
+      colored (~> 1.2)
+      mercenary (~> 0.3.2)
+      nokogiri (~> 1.5)
+      parallel (~> 1.3)
+      typhoeus (~> 0.6.7)
+      yell (~> 2.0)
     jekyll (2.4.0)
       classifier-reborn (~> 2.0)
       colorator (~> 0.1)
@@ -58,6 +68,9 @@ GEM
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9)
     mercenary (0.3.4)
+    mini_portile (0.6.0)
+    nokogiri (1.6.3.1)
+      mini_portile (= 0.6.0)
     octopress (3.0.0.rc.15)
       jekyll (~> 2.0)
       mercenary (~> 0.3.2)
@@ -75,6 +88,7 @@ GEM
       octopress-hooks (~> 2.0)
     octopress-hooks (2.2.1)
       jekyll (~> 2.0)
+    parallel (1.3.2)
     parslet (1.5.0)
       blankslate (~> 2.0)
     posix-spawn (0.3.9)
@@ -92,12 +106,16 @@ GEM
     titlecase (0.1.1)
     toml (0.1.1)
       parslet (~> 1.5.0)
+    typhoeus (0.6.9)
+      ethon (>= 0.7.1)
     yajl-ruby (1.1.0)
+    yell (2.0.4)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   gsl!
+  html-proofer
   narray!
   octopress (~> 3.0.0.rc.15)