diff --git a/sys/dev/usb/net/if_mos.c b/sys/dev/usb/net/if_mos.c
--- a/sys/dev/usb/net/if_mos.c
+++ b/sys/dev/usb/net/if_mos.c
@@ -424,11 +424,8 @@
 mos_miibus_readreg(device_t dev, int phy, int reg)
 {
 	struct mos_softc *sc = device_get_softc(dev);
-	uWord val;
 	int i, res, locked;
 
-	USETW(val, 0);
-
 	locked = mtx_owned(&sc->sc_mtx);
 	if (!locked)
 		MOS_LOCK(sc);