Index: Lib/StringIO.py
===================================================================
--- Lib/StringIO.py	(revision 41468)
+++ Lib/StringIO.py	(working copy)
@@ -72,8 +72,7 @@
         method is called repeatedly. This method returns the next input line,
         or raises StopIteration when EOF is hit.
         """
-        if self.closed:
-            raise StopIteration
+        _complain_ifclosed(self.closed)
         r = self.readline()
         if not r:
             raise StopIteration
Index: Lib/test/test_StringIO.py
===================================================================
--- Lib/test/test_StringIO.py	(revision 41468)
+++ Lib/test/test_StringIO.py	(working copy)
@@ -87,6 +87,8 @@
             eq(line, self._line + '\n')
             i += 1
         eq(i, 5)
+        self._fp.close()
+        self.assertRaises(ValueError, self._fp.next)
 
 class TestStringIO(TestGenericStringIO):
     MODULE = StringIO