diff --git a/dnsbl_exporter.rb b/dnsbl_exporter.rb
index 23532da..60ebea2 100644
--- a/dnsbl_exporter.rb
+++ b/dnsbl_exporter.rb
@@ -3,6 +3,7 @@ require 'prometheus/client'
 require 'prometheus/client/formats/text'
 require 'net/dns'
 require 'ostruct'
+require 'yaml'
 
 class DnsblCollector
 	class <<self