diff --git a/Lib/test/list_tests.py b/Lib/test/list_tests.py
index b3f24d3..c9aa316 100644
--- a/Lib/test/list_tests.py
+++ b/Lib/test/list_tests.py
@@ -84,6 +84,8 @@
         self.assertRaises(StopIteration, r.next)
         self.assertEqual(list(reversed(self.type2test())),
                          self.type2test())
+        # Bug 3689: make sure list-reversed-iterator doesn't have __len__
+        self.assertRaises(TypeError, len, reversed([1,2,3]))
 
     def test_setitem(self):
         a = self.type2test([0, 1])
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index cbc7165..c978779 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -50,7 +50,7 @@
         # verify expected attributes exist
         f = self.f
 
-        self.assertEquals(f.mode, "w")
+        self.assertEquals(f.mode, "wb")
         self.assertEquals(f.closed, False)
 
         # verify the attributes are readonly
@@ -160,7 +160,7 @@
 
     def testModeStrings(self):
         # check invalid mode strings
-        for mode in ("", "aU", "wU+", "rb", "rt"):
+        for mode in ("", "aU", "wU+", "rw", "rt"):
             try:
                 f = _fileio._FileIO(TESTFN, mode)
             except ValueError:
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index c9bd38d..eb41d1f 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -1266,7 +1266,7 @@
 
     def test_attributes(self):
         f = io.open(test_support.TESTFN, "wb", buffering=0)
-        self.assertEquals(f.mode, "w")
+        self.assertEquals(f.mode, "wb")
         f.close()
 
         f = io.open(test_support.TESTFN, "U")
@@ -1274,18 +1274,18 @@
         self.assertEquals(f.buffer.name,     test_support.TESTFN)
         self.assertEquals(f.buffer.raw.name, test_support.TESTFN)
         self.assertEquals(f.mode,            "U")
-        self.assertEquals(f.buffer.mode,     "r")
-        self.assertEquals(f.buffer.raw.mode, "r")
+        self.assertEquals(f.buffer.mode,     "rb")
+        self.assertEquals(f.buffer.raw.mode, "rb")
         f.close()
 
         f = io.open(test_support.TESTFN, "w+")
         self.assertEquals(f.mode,            "w+")
-        self.assertEquals(f.buffer.mode,     "r+") # Does it really matter?
-        self.assertEquals(f.buffer.raw.mode, "r+")
+        self.assertEquals(f.buffer.mode,     "rb+") # Does it really matter?
+        self.assertEquals(f.buffer.raw.mode, "rb+")
 
         g = io.open(f.fileno(), "wb", closefd=False)
-        self.assertEquals(g.mode,     "w")
-        self.assertEquals(g.raw.mode, "w")
+        self.assertEquals(g.mode,     "wb")
+        self.assertEquals(g.raw.mode, "wb")
         self.assertEquals(g.name,     f.fileno())
         self.assertEquals(g.raw.name, f.fileno())
         f.close()