diff --git a/config/initializers/prometheus_exporter.rb b/config/initializers/prometheus_exporter.rb
index 197777e3b6..fab095658f 100644
--- a/config/initializers/prometheus_exporter.rb
+++ b/config/initializers/prometheus_exporter.rb
@@ -2,6 +2,7 @@
 
 if ENV['MASTODON_PROMETHEUS_EXPORTER_ENABLED'] == 'true'
   if ENV['MASTODON_PROMETHEUS_EXPORTER_LOCAL'] == 'true'
+    require 'prometheus_exporter'
     require 'prometheus_exporter/server'
     require 'prometheus_exporter/client'