diff --git a/src/zope/interface/common/__init__.py b/src/zope/interface/common/__init__.py
index 1b8fd6ad..acbc5816 100644
--- a/src/zope/interface/common/__init__.py
+++ b/src/zope/interface/common/__init__.py
@@ -110,7 +110,7 @@ class ABCInterfaceClass(InterfaceClass):
     classes specifically registered with the ABC should be declared to
     do so.
 
-    .. verisonadded:: 5.0
+    .. versionadded:: 5.0.0
     """
 
     # If we could figure out invalidation, and used some special
diff --git a/src/zope/interface/common/io.py b/src/zope/interface/common/io.py
index d55f7d67..540d53ac 100644
--- a/src/zope/interface/common/io.py
+++ b/src/zope/interface/common/io.py
@@ -21,14 +21,6 @@
 from __future__ import absolute_import
 
 import io as abc
-try:
-    import cStringIO
-    import StringIO
-except ImportError:
-    # Python 3
-    extra_buffered_io_base = ()
-else:
-    extra_buffered_io_base = (StringIO.StringIO, cStringIO.InputType, cStringIO.OutputType)
 
 from zope.interface.common import ABCInterface
 
@@ -45,7 +37,16 @@ class IRawIOBase(IIOBase):
 
 class IBufferedIOBase(IIOBase):
     abc = abc.BufferedIOBase
-    extra_classes = extra_buffered_io_base
+    try:
+        import cStringIO
+    except ImportError:
+        # Python 3
+        extra_classes = ()
+    else:
+        import StringIO
+        extra_classes = (StringIO.StringIO, cStringIO.InputType, cStringIO.OutputType)
+        del cStringIO
+        del StringIO
 
 
 class ITextIOBase(IIOBase):
diff --git a/src/zope/interface/common/numbers.py b/src/zope/interface/common/numbers.py
index e62ca304..3bf9206b 100644
--- a/src/zope/interface/common/numbers.py
+++ b/src/zope/interface/common/numbers.py
@@ -45,6 +45,7 @@ def __complex__():
         """
         Rarely implemented, even in builtin types.
         """
+
     if PY2:
         @optional
         def __eq__(other):
diff --git a/src/zope/interface/common/tests/__init__.py b/src/zope/interface/common/tests/__init__.py
index ae992132..059e46cf 100644
--- a/src/zope/interface/common/tests/__init__.py
+++ b/src/zope/interface/common/tests/__init__.py
@@ -46,8 +46,11 @@ def iter_abc_interfaces(predicate=lambda iface: True):
 def add_abc_interface_tests(cls, module):
     def predicate(iface):
         return iface.__module__ == module
+    add_verify_tests(cls, iter_abc_interfaces(predicate))
 
-    for iface, registered_classes in iter_abc_interfaces(predicate):
+
+def add_verify_tests(cls, iface_classes_iter):
+    for iface, registered_classes in iface_classes_iter:
         for stdlib_class in registered_classes:
 
             def test(self, stdlib_class=stdlib_class, iface=iface):
@@ -62,7 +65,6 @@ def test(self, stdlib_class=stdlib_class, iface=iface):
             setattr(cls, name, test)
 
 
-
 class VerifyClassMixin(unittest.TestCase):
     verifier = staticmethod(verifyClass)
     UNVERIFIABLE = ()
@@ -92,4 +94,7 @@ def _adjust_object_before_verify(self, iface, x):
         if constructor is unittest.SkipTest:
             self.skipTest("Cannot create " + str(x))
 
-        return constructor()
+        result = constructor()
+        if hasattr(result, 'close'):
+            self.addCleanup(result.close)
+        return result
diff --git a/src/zope/interface/common/tests/test_builtins.py b/src/zope/interface/common/tests/test_builtins.py
index e42393bc..1f0d3383 100644
--- a/src/zope/interface/common/tests/test_builtins.py
+++ b/src/zope/interface/common/tests/test_builtins.py
@@ -18,38 +18,24 @@
 
 from . import VerifyClassMixin
 from . import VerifyObjectMixin
+from . import add_verify_tests
 
 
 class TestVerifyClass(VerifyClassMixin,
                       unittest.TestCase):
-    UNVERIFIABLE = (
-
-    )
-    FILE_IMPL = ()
-    if PY2:
-        FILE_IMPL = ((file, builtins.IFile),)
-    @classmethod
-    def create_tests(cls):
-        for klass, iface in (
-                (list, builtins.IList),
-                (tuple, builtins.ITuple),
-                (type(u'abc'), builtins.ITextString),
-                (bytes, builtins.IByteString),
-                (str, builtins.INativeString),
-                (bool, builtins.IBool),
-                (dict, builtins.IDict),
-        ) + cls.FILE_IMPL:
-            def test(self, klass=klass, iface=iface):
-                if klass in self.UNVERIFIABLE:
-                    self.skipTest("Cannot verify %s" % klass)
-
-                self.assertTrue(self.verify(iface, klass))
-
-            name = 'test_auto_' + klass.__name__ + '_' + iface.__name__
-            test.__name__ = name
-            setattr(cls, name, test)
-
-TestVerifyClass.create_tests()
+    pass
+
+
+add_verify_tests(TestVerifyClass, (
+    (builtins.IList, (list,)),
+    (builtins.ITuple, (tuple,)),
+    (builtins.ITextString, (type(u'abc'),)),
+    (builtins.IByteString, (bytes,)),
+    (builtins.INativeString, (str,)),
+    (builtins.IBool, (bool,)),
+    (builtins.IDict, (dict,)),
+    (builtins.IFile, (file,) if PY2 else ()),
+))
 
 
 class TestVerifyObject(VerifyObjectMixin,