diff --git a/Mac/Lib/Audio_mac.py b/Mac/Lib/Audio_mac.py
index 450cdf1..27526b4 100644
--- a/Mac/Lib/Audio_mac.py
+++ b/Mac/Lib/Audio_mac.py
@@ -42,6 +42,7 @@
 		import time
 		from Sound import *
 		import struct
+		import MacOS
 		if not self._chan:
 			import Snd
 			self._chan = Snd.SndNewChannel(5, 0, self._callback)
@@ -56,7 +57,7 @@
 			import audioop
 			data = audioop.add(data, '\x80'*len(data), 1)
 		h1 = struct.pack('llhhllbbl',
-			id(data)+12,
+			id(data)+MacOS.string_id_to_data,
 			self._nchannels,
 			self._outrate, 0,
 			0,