diff -r 8885fc2e92b3 Lib/dbm/dumb.py
--- a/Lib/dbm/dumb.py	Tue May 13 11:30:17 2014 +0200
+++ b/Lib/dbm/dumb.py	Tue May 13 15:05:35 2014 +0300
@@ -125,8 +125,10 @@
     def __getitem__(self, key):
         if isinstance(key, str):
             key = key.encode('utf-8')
-        self._verify_open()
-        pos, siz = self._index[key]     # may raise KeyError
+        try:
+            pos, siz = self._index[key]     # may raise KeyError
+        except TypeError:
+            raise error('DBM object has already been closed') from None
         f = _io.open(self._datfile, 'rb')
         f.seek(pos)
         dat = f.read(siz)
@@ -178,8 +180,13 @@
             val = val.encode('utf-8')
         elif not isinstance(val, (bytes, bytearray)):
             raise TypeError("values must be bytes or strings")
-        self._verify_open()
-        if key not in self._index:
+        
+        try:
+            found = key in self._index
+        except TypeError:
+            raise error('DBM object has already been closed') from None
+
+        if not found:
             self._addkey(key, self._addval(val))
         else:
             # See whether the new value is small enough to fit in the
@@ -206,9 +213,11 @@
     def __delitem__(self, key):
         if isinstance(key, str):
             key = key.encode('utf-8')
-        self._verify_open()
         # The blocks used by the associated value are lost.
-        del self._index[key]
+        try:
+            del self._index[key]
+        except TypeError:
+            raise error('DBM object has already been closed') from None
         # XXX It's unclear why we do a _commit() here (the code always
         # XXX has, so I'm not changing it).  __setitem__ doesn't try to
         # XXX keep the directory file in synch.  Why should we?  Or
@@ -226,17 +235,21 @@
     def __contains__(self, key):
         if isinstance(key, str):
             key = key.encode('utf-8')
-        self._verify_open()
-        return key in self._index
+        try:
+            return key in self._index
+        except TypeError:
+            raise error('DBM object has already been closed') from None
 
     def iterkeys(self):
         self._verify_open()
         return iter(self._index.keys())
     __iter__ = iterkeys
 
-    def __len__(self):
-        self._verify_open()
-        return len(self._index)
+    def __len__(self):        
+        try:
+            return len(self._index)
+        except TypeError:
+            raise error('DBM object has already been closed') from None
 
     def close(self):
         self._commit()