#define L2CAP_DEFAULT_MIN_MTU          48
 #define L2CAP_DEFAULT_FLUSH_TO         0xffff
 #define L2CAP_DEFAULT_TX_WINDOW                63
-#define L2CAP_DEFAULT_NUM_TO_ACK        (L2CAP_DEFAULT_TX_WINDOW/5)
 #define L2CAP_DEFAULT_MAX_TX           3
 #define L2CAP_DEFAULT_RETRANS_TO       1000    /* 1 second */
 #define L2CAP_DEFAULT_MONITOR_TO       12000   /* 12 seconds */
        __u8            frames_sent;
        __u8            unacked_frames;
        __u8            retry_count;
-       __u8            num_to_ack;
+       __u8            num_acked;
        __u16           sdu_len;
        __u16           partial_sdu_len;
        struct sk_buff  *sdu;
 
        l2cap_pi(sk)->expected_ack_seq = 0;
        l2cap_pi(sk)->unacked_frames = 0;
        l2cap_pi(sk)->buffer_seq = 0;
-       l2cap_pi(sk)->num_to_ack = 0;
+       l2cap_pi(sk)->num_acked = 0;
        l2cap_pi(sk)->frames_sent = 0;
 
        setup_timer(&l2cap_pi(sk)->retrans_timer,
        u8 tx_seq = __get_txseq(rx_control);
        u8 req_seq = __get_reqseq(rx_control);
        u8 sar = rx_control >> L2CAP_CTRL_SAR_SHIFT;
+       int num_to_ack = (pi->tx_win/6) + 1;
        int err = 0;
 
        BT_DBG("sk %p rx_control 0x%4.4x len %d", sk, rx_control, skb->len);
 
        __mod_ack_timer();
 
-       pi->num_to_ack = (pi->num_to_ack + 1) % L2CAP_DEFAULT_NUM_TO_ACK;
-       if (pi->num_to_ack == L2CAP_DEFAULT_NUM_TO_ACK - 1)
+       pi->num_acked = (pi->num_acked + 1) % num_to_ack;
+       if (pi->num_acked == num_to_ack - 1)
                l2cap_send_ack(pi);
 
        return 0;