diff --git a/Gemfile b/Gemfile
index 576ad34e..102f8a17 100644
--- a/Gemfile
+++ b/Gemfile
@@ -12,3 +12,5 @@ gem "webrick", "~> 1.9"
 gem 'html-proofer', "~> 3.19.4"
 
 gem 'json'
+
+gem 'erb'
diff --git a/Gemfile.lock b/Gemfile.lock
index a1348dec..466a4b43 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -30,6 +30,7 @@ GEM
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
+    erb (6.0.3)
     ethon (0.16.0)
       ffi (>= 1.15.0)
     eventmachine (1.2.7)
@@ -295,6 +296,7 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  erb
   github-pages (= 232)
   html-proofer (~> 3.19.4)
   json