return -1;
 
        hdrlen = ieee80211_hdrlen(hdr->frame_control);
-
-       if (skb->len < 8 + hdrlen)
+       if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN)
                return -1;
 
-       len = skb->len - hdrlen - 8;
+       len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN;
 
        keyidx = skb->data[hdrlen + 3] >> 6;
 
        } else if (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) {
                ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
                /* remove ICV */
-               skb_trim(rx->skb, rx->skb->len - 4);
+               skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN);
        }
 
        return RX_CONTINUE;