diff --git a/Lib/wave.py b/Lib/wave.py
index 2877137..54f0302 100644
--- a/Lib/wave.py
+++ b/Lib/wave.py
@@ -261,9 +261,9 @@
     #
 
     def _read_fmt_chunk(self, chunk):
-        wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack_from('<hhllh', chunk.read(14))
+        wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack_from('<HHLLH', chunk.read(14))
         if wFormatTag == WAVE_FORMAT_PCM:
-            sampwidth = struct.unpack_from('<h', chunk.read(2))[0]
+            sampwidth = struct.unpack_from('<H', chunk.read(2))[0]
             self._sampwidth = (sampwidth + 7) // 8
         else:
             raise Error('unknown format: %r' % (wFormatTag,))
@@ -466,14 +466,14 @@
             self._nframes = initlength // (self._nchannels * self._sampwidth)
         self._datalength = self._nframes * self._nchannels * self._sampwidth
         self._form_length_pos = self._file.tell()
-        self._file.write(struct.pack('<l4s4slhhllhh4s',
+        self._file.write(struct.pack('<L4s4sLHHLLHH4s',
             36 + self._datalength, b'WAVE', b'fmt ', 16,
             WAVE_FORMAT_PCM, self._nchannels, self._framerate,
             self._nchannels * self._framerate * self._sampwidth,
             self._nchannels * self._sampwidth,
             self._sampwidth * 8, b'data'))
         self._data_length_pos = self._file.tell()
-        self._file.write(struct.pack('<l', self._datalength))
+        self._file.write(struct.pack('<L', self._datalength))
         self._headerwritten = True
 
     def _patchheader(self):
@@ -482,9 +482,9 @@
             return
         curpos = self._file.tell()
         self._file.seek(self._form_length_pos, 0)
-        self._file.write(struct.pack('<l', 36 + self._datawritten))
+        self._file.write(struct.pack('<L', 36 + self._datawritten))
         self._file.seek(self._data_length_pos, 0)
-        self._file.write(struct.pack('<l', self._datawritten))
+        self._file.write(struct.pack('<L', self._datawritten))
         self._file.seek(curpos, 0)
         self._datalength = self._datawritten