diff --git a/lib/bundler/multilock/lockfile_generator.rb b/lib/bundler/multilock/lockfile_generator.rb
index 7f8011f..0428542 100644
--- a/lib/bundler/multilock/lockfile_generator.rb
+++ b/lib/bundler/multilock/lockfile_generator.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "delegate"
+
 require "bundler/lockfile_generator"
 
 module Bundler