diff --git a/Lib/inspect.py b/Lib/inspect.py
index 45515fca566..54365313b1f 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -63,7 +63,7 @@ def isclass(object):
     Class objects provide these attributes:
         __doc__         documentation string
         __module__      name of module in which this class was defined"""
-    return isinstance(object, type) or hasattr(object, '__bases__')
+    return isinstance(object, type)
 
 def ismethod(object):
     """Return true if the object is an instance method.
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index b3aa28cf7ca..e2fe641ec03 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -74,7 +74,6 @@ class TestPredicates(IsTestBase):
     def test_excluding_predicates(self):
         self.istest(inspect.isbuiltin, 'sys.exit')
         self.istest(inspect.isbuiltin, '[].append')
-        self.istest(inspect.isclass, 'mod.StupidGit')
         self.istest(inspect.iscode, 'mod.spam.__code__')
         self.istest(inspect.isframe, 'tb.tb_frame')
         self.istest(inspect.isfunction, 'mod.spam')
@@ -99,6 +98,15 @@ class TestPredicates(IsTestBase):
         self.assert_(inspect.isroutine(mod.spam))
         self.assert_(inspect.isroutine([].count))
 
+    def test_isclass(self):
+        self.istest(inspect.isclass, 'mod.StupidGit')
+        self.assertTrue(inspect.isclass(list))
+
+        class CustomGetattr(object):
+            def __getattr__(self, attr):
+                return None
+        self.assertFalse(inspect.isclass(CustomGetattr()))
+
     def test_get_slot_members(self):
         class C(object):
             __slots__ = ("a", "b")