diff --git a/src/emu/machine/scsi.c b/src/emu/machine/scsi.c
index 33097caffb7..c00febc6a3a 100644
--- a/src/emu/machine/scsi.c
+++ b/src/emu/machine/scsi.c
@@ -7,57 +7,90 @@ void SCSIAllocInstance( const SCSIClass *scsiClass, SCSIInstance **instance, int
 
 void SCSIDeleteInstance( SCSIInstance *instance )
 {
-	instance->scsiClass->dispatch( SCSIOP_DELETE_INSTANCE, instance, 0, NULL );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_DELETE_INSTANCE, instance, 0, NULL );
+	}
 }
 
 void SCSISetDevice( SCSIInstance *instance, void *device )
 {
-	instance->scsiClass->dispatch( SCSIOP_SET_DEVICE, instance, 0, device );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_SET_DEVICE, instance, 0, device );
+	}
 }
 
 void SCSIGetDevice( SCSIInstance *instance, void **device )
 {
-	instance->scsiClass->dispatch( SCSIOP_GET_DEVICE, instance, 0, device );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_GET_DEVICE, instance, 0, device );
+	}
 }
 
 void SCSIReset( SCSIInstance *instance )
 {
-	instance->scsiClass->dispatch( SCSIOP_RESET_DEVICE, instance, 0, NULL );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_RESET_DEVICE, instance, 0, NULL );
+	}
 }
 
 void SCSIExecCommand( SCSIInstance *instance, int *resultLength )
 {
-	*resultLength = instance->scsiClass->dispatch( SCSIOP_EXEC_COMMAND, instance, 0, NULL );
+	if (instance)
+	{
+		*resultLength = instance->scsiClass->dispatch( SCSIOP_EXEC_COMMAND, instance, 0, NULL );
+	}
 }
 
 void SCSISetCommand( SCSIInstance *instance, UINT8 *command, int commandLength )
 {
-	instance->scsiClass->dispatch( SCSIOP_SET_COMMAND, instance, commandLength, command );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_SET_COMMAND, instance, commandLength, command );
+	}
 }
 
 void SCSIGetCommand( SCSIInstance *instance, UINT8 **command, int *commandLength )
 {
-	*commandLength = instance->scsiClass->dispatch( SCSIOP_GET_COMMAND, instance, 0, command );
+	if (instance)
+	{
+		*commandLength = instance->scsiClass->dispatch( SCSIOP_GET_COMMAND, instance, 0, command );
+	}
 }
 
 void SCSIWriteData( SCSIInstance *instance, void *data, int dataLength )
 {
-	instance->scsiClass->dispatch( SCSIOP_WRITE_DATA, instance, dataLength, data );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_WRITE_DATA, instance, dataLength, data );
+	}
 }
 
 void SCSIReadData( SCSIInstance *instance, void *data, int dataLength )
 {
-	instance->scsiClass->dispatch( SCSIOP_READ_DATA, instance, dataLength, data );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_READ_DATA, instance, dataLength, data );
+	}
 }
 
 void SCSISetPhase( SCSIInstance *instance, int phase )
 {
-	instance->scsiClass->dispatch( SCSIOP_SET_PHASE, instance, phase, NULL );
+	if (instance)
+	{
+		instance->scsiClass->dispatch( SCSIOP_SET_PHASE, instance, phase, NULL );
+	}
 }
 
 void SCSIGetPhase( SCSIInstance *instance, int *phase )
 {
-	*phase = instance->scsiClass->dispatch( SCSIOP_GET_PHASE, instance, 0, NULL );
+	if (instance)
+	{
+		*phase = instance->scsiClass->dispatch( SCSIOP_GET_PHASE, instance, 0, NULL );
+	}
 }
 
 int SCSIBase( const SCSIClass *scsiClass, int operation, void *file, INT64 intparm, UINT8 *ptrparm )