diff --git a/Lib/test/test_sax.py b/Lib/test/test_sax.py
index 78a1c697c50..cfa18f7da5e 100644
--- a/Lib/test/test_sax.py
+++ b/Lib/test/test_sax.py
@@ -578,13 +578,14 @@ class StreamReaderWriterXmlgenTest(XmlgenTest, unittest.TestCase):
             writer.close()
             support.unlink(self.fname)
         self.addCleanup(cleanup)
-        writer.getvalue = self.getvalue
+        def getvalue():
+            # Windows will not let use reopen without first closing
+            writer.close()
+            with open(writer.name, 'rb') as f:
+                return f.read()
+        writer.getvalue = getvalue
         return writer
 
-    def getvalue(self):
-        with open(self.fname, 'rb') as f:
-            return f.read()
-
     def xml(self, doc, encoding='iso-8859-1'):
         return ('<?xml version="1.0" encoding="%s"?>\n%s' %
                 (encoding, doc)).encode('ascii', 'xmlcharrefreplace')