diff --git a/Gemfile b/Gemfile
index fd9d00b0..677e6522 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,6 +14,7 @@ group :benchmark, :test do
   gem 'memory_profiler'
   gem 'terminal-table'
   gem "lru_redux"
+  gem "webrick"
 
   install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ && RUBY_ENGINE != 'truffleruby' } do
     gem 'stackprof'