diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index f0b38b6..02533c9 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -1299,13 +1299,13 @@
     def testImport__all__(self):
         for name in io.__all__:
             obj = getattr(io, name, None)
-            self.assert_(obj is not None, name)
+            self.assertTrue(obj is not None, name)
             if name == "open":
                 continue
             elif "error" in name.lower():
-                self.assert_(issubclass(obj, Exception), name)
-            else:
-                self.assert_(issubclass(obj, io.IOBase))
+                self.assertTrue(issubclass(obj, Exception), name)
+            elif not name.startswith("SEEK_"):
+                self.assertTrue(issubclass(obj, io.IOBase))
 
 
     def test_attributes(self):