diff --git a/lib/middleman/features/slickmap.rb b/lib/middleman/features/slickmap.rb
index 33b8f71e..3e50d878 100644
--- a/lib/middleman/features/slickmap.rb
+++ b/lib/middleman/features/slickmap.rb
@@ -6,6 +6,7 @@ rescue LoadError
 end
 
 if Middleman::Base.environment == "build"
+  require "middleman/builder"
   Middleman::Builder.template :slickmap, "sitemap.html", "sitemap.html"
 end