diff --git a/scrapy/spidermanager.py b/scrapy/spidermanager.py
index ce2e36f31..5a0951cb4 100644
--- a/scrapy/spidermanager.py
+++ b/scrapy/spidermanager.py
@@ -3,7 +3,7 @@ SpiderManager is the class which locates and manages all website-specific
 spiders
 """
 
-from zope.interface import implements
+from zope.interface import implementer
 import six
 
 from scrapy import signals
@@ -12,10 +12,9 @@ from scrapy.utils.misc import walk_modules
 from scrapy.utils.spider import iter_spider_classes
 
 
+@implementer(ISpiderManager)
 class SpiderManager(object):
 
-    implements(ISpiderManager)
-
     def __init__(self, spider_modules):
         self.spider_modules = spider_modules
         self._spiders = {}
diff --git a/scrapy/utils/spider.py b/scrapy/utils/spider.py
index d97b8a841..4e43bc13f 100644
--- a/scrapy/utils/spider.py
+++ b/scrapy/utils/spider.py
@@ -1,5 +1,7 @@
 import inspect
 
+import six
+
 from scrapy import log
 from scrapy.item import BaseItem
 from scrapy.utils.misc import  arg_to_iter
@@ -16,7 +18,7 @@ def iter_spider_classes(module):
     # singleton in scrapy.spider.spiders
     from scrapy.spider import Spider
 
-    for obj in vars(module).itervalues():
+    for obj in six.itervalues(vars(module)):
         if inspect.isclass(obj) and \
            issubclass(obj, Spider) and \
            obj.__module__ == module.__name__ and \
diff --git a/tests/py3-ignores.txt b/tests/py3-ignores.txt
index d1831c266..e2254b77e 100644
--- a/tests/py3-ignores.txt
+++ b/tests/py3-ignores.txt
@@ -69,7 +69,6 @@ tests/test_utils_request.py
 tests/test_utils_response.py
 tests/test_utils_serialize.py
 tests/test_utils_signal.py
-tests/test_utils_spider.py
 tests/test_utils_template.py
 tests/test_utils_url.py
 tests/test_webclient.py
diff --git a/tests/test_utils_spider.py b/tests/test_utils_spider.py
index 405b36715..334ec00f3 100644
--- a/tests/test_utils_spider.py
+++ b/tests/test_utils_spider.py
@@ -30,7 +30,7 @@ class UtilsSpidersTestCase(unittest.TestCase):
     def test_iter_spider_classes(self):
         import tests.test_utils_spider
         it = iter_spider_classes(tests.test_utils_spider)
-        self.assertEqual(set(it), set([MySpider1, MySpider2]))
+        self.assertEqual(set(it), {MySpider1, MySpider2})
 
 if __name__ == "__main__":
     unittest.main()