--- src/sys/dev/netif/rum/if_rum.c	2007/07/27 18:07:21	1.18
+++ src/sys/dev/netif/rum/if_rum.c	2007/10/28 02:29:07	1.19
@@ -739,7 +739,7 @@ rum_newstate(struct ieee80211com *ic, en
 /* quickly determine if a given rate is CCK or OFDM */
 #define RUM_RATE_IS_OFDM(rate)	((rate) >= 12 && (rate) != 22)
 
-#define RUM_ACK_SIZE	(sizeof(struct ieee80211_frame_ack) + IEEE80211_FCS_LEN)
+#define RUM_ACK_SIZE	(sizeof(struct ieee80211_frame_ack) + IEEE80211_CRC_LEN)
 
 static void
 rum_txeof(usbd_xfer_handle xfer, usbd_private_handle priv, usbd_status status)