diff --git a/middleman-core/lib/middleman-core/core_extensions/request.rb b/middleman-core/lib/middleman-core/core_extensions/request.rb
index e78f0ffe..aabb708e 100644
--- a/middleman-core/lib/middleman-core/core_extensions/request.rb
+++ b/middleman-core/lib/middleman-core/core_extensions/request.rb
@@ -281,7 +281,7 @@ module Middleman
         # Halt request and return 404
         def not_found(res, path)
           res.status = 404
-          res.write "<html><body><h1>File Not Found</h1><p>#{path}</p></body>"
+          res.write "<html><head></head><body><h1>File Not Found</h1><p>#{path}</p></body></html>"
           res.finish
         end
 
