const struct net_device *indev,
                        const struct net_device *outdev,
                        const struct nf_loginfo *li,
-                       const char *prefix)
+                       const char *prefix, unsigned int plen)
 {
        unsigned char *old_tail;
        struct nfulnl_msg_packet_hdr pmsg;
 
        NFA_PUT(inst->skb, NFULA_PACKET_HDR, sizeof(pmsg), &pmsg);
 
-       if (prefix) {
-               int slen = strlen(prefix);
-               if (slen > NFULNL_PREFIXLEN)
-                       slen = NFULNL_PREFIXLEN;
-               NFA_PUT(inst->skb, NFULA_PREFIX, slen, prefix);
-       }
+       if (prefix)
+               NFA_PUT(inst->skb, NFULA_PREFIX, plen, prefix);
 
        if (indev) {
                tmp_uint = htonl(indev->ifindex);
        const struct nf_loginfo *li;
        unsigned int qthreshold;
        unsigned int nlbufsiz;
+       unsigned int plen;
 
        if (li_user && li_user->type == NF_LOG_TYPE_ULOG) 
                li = li_user;
                return;
        }
 
+       plen = 0;
+       if (prefix)
+               plen = strlen(prefix);
+
        /* all macros expand to constant values at compile time */
        /* FIXME: do we want to make the size calculation conditional based on
         * what is actually present?  way more branches and checks, but more
 #endif
                + NFA_SPACE(sizeof(u_int32_t))  /* mark */
                + NFA_SPACE(sizeof(u_int32_t))  /* uid */
-               + NFA_SPACE(NFULNL_PREFIXLEN)   /* prefix */
+               + NFA_SPACE(plen)               /* prefix */
                + NFA_SPACE(sizeof(struct nfulnl_msg_packet_hw))
                + NFA_SPACE(sizeof(struct nfulnl_msg_packet_timestamp));
 
        inst->qlen++;
 
        __build_packet_message(inst, skb, data_len, pf,
-                               hooknum, in, out, li, prefix);
+                               hooknum, in, out, li, prefix, plen);
 
        /* timer_pending always called within inst->lock, so there
         * is no chance of a race here */