diff --git a/tests/test_crawl.py b/tests/test_crawl.py
index 0c64948fa..d5babdded 100644
--- a/tests/test_crawl.py
+++ b/tests/test_crawl.py
@@ -92,7 +92,7 @@ class CrawlTestCase(TestCase):
         crawler = self.runner.create_crawler(SimpleSpider)
         with LogCapture() as l:
             # try to fetch the homepage of a non-existent domain
-            yield crawler.crawl("http://dns.resolution.invalid/")
+            yield crawler.crawl("http://dns.resolution.invalid./")
         self._assert_retried(l)
 
     @defer.inlineCallbacks