{
                u_int16_t *p = (u_int16_t *) skb->data;
 
-               *p = 0; /* indicate inbound in DLT_LINUX_SLL */
+               *p = 0; /* indicate inbound */
        }
 
        if (is->pass_filter
        /* check if we should pass this packet
         * the filter instructions are constructed assuming
         * a four-byte PPP header on each packet */
-       skb_push(skb, 4);
+       *skb_push(skb, 4) = 1; /* indicate outbound */
 
        {
                u_int16_t *p = (u_int16_t *) skb->data;
 
-               *p++ = htons(4); /* indicate outbound in DLT_LINUX_SLL */
+               p++;
                *p   = htons(proto);
        }
 
         * temporarily remove part of the fake header stuck on
         * earlier.
         */
-       skb_pull(skb, IPPP_MAX_HEADER - 4);
+       *skb_pull(skb, IPPP_MAX_HEADER - 4) = 1; /* indicate outbound */
 
        {
                u_int16_t *p = (u_int16_t *) skb->data;
 
-               *p++ = htons(4);        /* indicate outbound in DLT_LINUX_SLL */
+               p++;
                *p   = htons(proto);
        }