diff --git a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.cpp b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.cpp
index 5f7cead58c..33cee3c60c 100644
--- a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.cpp
+++ b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.cpp
@@ -8,6 +8,16 @@
 #include <unistd.h>
 #include <Carbon/Carbon.h>
 
+MemoryCardDriverThreaded_OSX::MemoryCardDriverThreaded_OSX()
+{
+	DarwinMCHelpers::Start();
+}
+
+MemoryCardDriverThreaded_OSX::~MemoryCardDriverThreaded_OSX()
+{
+	DarwinMCHelpers::Stop();
+}
+
 void MemoryCardDriverThreaded_OSX::Flush( UsbStorageDevice *pDevice )
 {
 	if( pDevice->iRefNum == -1 )
@@ -23,6 +33,11 @@ void MemoryCardDriverThreaded_OSX::Flush( UsbStorageDevice *pDevice )
 		LOG->Warn( "Failed to flush the memory card." );
 }
 
+bool MemoryCardDriverThreaded_OSX::USBStorageDevicesChanged()
+{
+	return DarwinMCHelpers::DevicesChanged();
+}
+
 void MemoryCardDriverThreaded_OSX::GetUSBStorageDevices( vector<UsbStorageDevice>& vDevicesOut )
 {
 	LOG->Trace( "GetUSBStorageDevices." );
diff --git a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.h b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.h
index 8b6991b812..16c88e3384 100644
--- a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.h
+++ b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_OSX.h
@@ -5,12 +5,15 @@
 
 class MemoryCardDriverThreaded_OSX : public MemoryCardDriver
 {
-public:	
+public:
+	MemoryCardDriverThreaded_OSX();
+	~MemoryCardDriverThreaded_OSX();
 	bool Mount( UsbStorageDevice *pDevice ) { return true; }
 	void Unmount( UsbStorageDevice *pDevice ) { }
 	void Flush( UsbStorageDevice *pDevice );
 	
 protected:
+	bool USBStorageDevicesChanged();
 	void GetUSBStorageDevices( vector<UsbStorageDevice>& vStorageDevicesOut );
 	bool TestWrite( UsbStorageDevice *pDevice );
 };
diff --git a/stepmania/src/archutils/Darwin/DarwinMCHelpers.h b/stepmania/src/archutils/Darwin/DarwinMCHelpers.h
index fca7f103a4..9fdb0cb513 100644
--- a/stepmania/src/archutils/Darwin/DarwinMCHelpers.h
+++ b/stepmania/src/archutils/Darwin/DarwinMCHelpers.h
@@ -3,7 +3,10 @@
 
 namespace DarwinMCHelpers
 {
-	void GetRemovableDevicePaths( vector<CString> vDevicePaths );
+	void Start();
+	void Stop();
+	bool DevicesChanged();
+	void GetRemovableDevicePaths( vector<CString>& vDevicePaths );
 }
 
 #endif
diff --git a/stepmania/src/archutils/Darwin/DarwinMCHelpers.mm b/stepmania/src/archutils/Darwin/DarwinMCHelpers.mm
index 75e1aa1849..ed81331448 100644
--- a/stepmania/src/archutils/Darwin/DarwinMCHelpers.mm
+++ b/stepmania/src/archutils/Darwin/DarwinMCHelpers.mm
@@ -1,19 +1,72 @@
 #include "global.h"
 #include "DarwinMCHelpers.h"
+#include "RageThreads.h"
 
 #import <Cocoa/Cocoa.h>
 
-void DarwinMCHelpers::GetRemovableDevicePaths( vector<CString> vDevicePaths )
+static bool g_bChange;
+static RageMutex g_Lock( "USB devices changed lock" );
+
+@interface MemoryCardHelper : NSObject
+- (void) devicesChanged:(NSNotification *)notification;
+@end
+@implementation MemoryCardHelper
+- (void) devicesChanged:(NSNotification *)notification
 {
+	LockMut(g_Lock);
+	g_bChange = true;
+}
+@end
+
+static MemoryCardHelper *g_MCH = nil;
+
+void DarwinMCHelpers::Start()
+{
+	ASSERT( g_MCH == nil );
+	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+	NSNotificationCenter *nc = [[NSWorkspace sharedWorkspace] notificationCenter];
+	
+	g_bChange = true;
+	g_MCH = [[MemoryCardHelper alloc] init];
+	[nc addObserver:g_MCH selector:@selector(devicesChanged:)
+			   name:@"NSWorkspaceDidMountNotification" object:nil];
+	[nc addObserver:g_MCH selector:@selector(devicesChanged:)
+			   name:@"NSWorkspaceDidUnmountNotification" object:nil];
+	
+	[pool release];
+}
+
+void DarwinMCHelpers::Stop()
+{
+	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+	NSNotificationCenter *nc = [[NSWorkspace sharedWorkspace] notificationCenter];
+
+	[nc removeObserver:g_MCH];
+	[g_MCH release];
+	
+	[pool release];
+}
+
+bool DarwinMCHelpers::DevicesChanged()
+{
+	LockMut( g_Lock );
+	return g_bChange;
+}
+
+void DarwinMCHelpers::GetRemovableDevicePaths( vector<CString>& vDevicePaths )
+{
+	LockMut( g_Lock );
 	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 	NSWorkspace *ws = [NSWorkspace sharedWorkspace];
 	NSArray *paths = [ws mountedRemovableMedia];
 	NSEnumerator *i = [paths objectEnumerator];
 	NSString *path;
 	
+	vDevicePaths.clear();
 	while( (path = [i nextObject]) )
 		vDevicePaths.push_back( [path UTF8String] );
 	[pool release];
+	g_bChange = false;
 }
 
 /*