diff --git a/scrapy/trunk/scrapy/contrib/spidermiddleware/duplicatesfilter.py b/scrapy/trunk/scrapy/contrib/spidermiddleware/duplicatesfilter.py
index d5f03b429..e6a8872ab 100644
--- a/scrapy/trunk/scrapy/contrib/spidermiddleware/duplicatesfilter.py
+++ b/scrapy/trunk/scrapy/contrib/spidermiddleware/duplicatesfilter.py
@@ -40,6 +40,7 @@ class DuplicatesFilterMiddleware(object):
 
     def process_spider_output(self, response, result, spider):
         domain = spider.domain_name
+        self.filter.add(domain, response.request)
 
         for req in result:
             if isinstance(req, Request):