--- rcxlib/RCX_USBTowerPipe_osx.cpp.orig	2011-05-08 18:40:04.000000000 -0700
+++ rcxlib/RCX_USBTowerPipe_osx.cpp	2011-05-08 18:40:07.000000000 -0700
@@ -90,7 +90,7 @@
 	};
 
 	static void ReadCompletionGlue(void *refCon, IOReturn result, void *arg0);
-	void		ReadCompletion(IOReturn result, UInt32 n);
+	void		ReadCompletion(IOReturn result, uintptr_t n);
 	void		StartRead();
 	void		ConsumeInBuffer();
 	void		SetTimeout(long timeout_ms);
@@ -288,7 +288,7 @@
 }
 
 
-void RCX_USBTowerPipe_osx::ReadCompletion(IOReturn result, UInt32 n)
+void RCX_USBTowerPipe_osx::ReadCompletion(IOReturn result, uintptr_t n)
 {
 	if (result == kIOReturnAborted) return;
 
@@ -328,7 +328,7 @@
 void RCX_USBTowerPipe_osx::ReadCompletionGlue(void *refCon, IOReturn result, void *arg0)
 {
 	RCX_USBTowerPipe_osx* pipe = (RCX_USBTowerPipe_osx*)refCon;
-	pipe->ReadCompletion(result, (UInt32)arg0);
+	pipe->ReadCompletion(result, (uintptr_t)arg0);
 }
 
 
