diff --git a/sys/dev/usb/umass.c b/sys/dev/usb/umass.c
index f2039c878f9f..5d0bd0523cf0 100644
--- a/sys/dev/usb/umass.c
+++ b/sys/dev/usb/umass.c
@@ -98,7 +98,7 @@ typedef struct umass_softc {
 
 #define USBD_COMMAND_FAILED	USBD_INVAL	/* redefine some errors for */
 
-#define UPROTO_MASS_ZIP	80
+#define UPROTO_MASS_ZIP		0x50		/* letter 'P' for protoype */
 
 #define UMASS_SCSIID_HOST	0x00
 #define UMASS_SCSIID_DEVICE	0x01