--- wave.py-old	2009-02-10 11:48:05.000000000 +0000
+++ wave.py	2009-02-10 11:48:35.000000000 +0000
@@ -462,14 +462,24 @@
         if not self._nframes:
             self._nframes = initlength / (self._nchannels * self._sampwidth)
         self._datalength = self._nframes * self._nchannels * self._sampwidth
-        self._form_length_pos = self._file.tell()
+        try:
+            self._form_length_pos = self._file.tell()
+        except IOError:
+            # tell will fail when the output is a pipe.  We don't care
+            # unless we end up patching the header.  If we do patch the
+            # header then _form_length_pos being unset will cause it to
+            # fail then.
+            pass
         self._file.write(struct.pack('<l4s4slhhllhh4s',
             36 + self._datalength, 'WAVE', 'fmt ', 16,
             WAVE_FORMAT_PCM, self._nchannels, self._framerate,
             self._nchannels * self._framerate * self._sampwidth,
             self._nchannels * self._sampwidth,
             self._sampwidth * 8, 'data'))
-        self._data_length_pos = self._file.tell()
+        try:
+            self._data_length_pos = self._file.tell()
+        except IOError:
+            pass
         self._file.write(struct.pack('<l', self._datalength))
 
     def _patchheader(self):