diff --git a/include/patty/ax25/sock.h b/include/patty/ax25/sock.h
index f87fdb0..cb1b739 100644
--- a/include/patty/ax25/sock.h
+++ b/include/patty/ax25/sock.h
@@ -32,10 +32,14 @@ enum patty_ax25_sock_opt {
     PATTY_AX25_SOCK_IF
 };
 
-typedef struct _patty_ax25_sock_tx_slot {
-    size_t len;
-    uint8_t buf[PATTY_AX25_SOCK_BUFSZ];
-} patty_ax25_sock_tx_slot;
+enum patty_ax25_sock_flags {
+    PATTY_AX25_SOCK_SREJ       = (1 << 2),
+    PATTY_AX25_SOCK_MODULO_8   = (1 << 3),
+    PATTY_AX25_SOCK_MODULO_128 = (1 << 4),
+    PATTY_AX25_SOCK_TEST       = (1 << 5),
+    PATTY_AX25_SOCK_SYNC_TX    = (1 << 6),
+    PATTY_AX25_SOCK_SEGMENTER  = (1 << 7)
+};
 
 typedef struct _patty_ax25_sock {
     enum patty_ax25_proto       proto;
@@ -54,6 +58,8 @@ typedef struct _patty_ax25_sock {
     unsigned int seq_send,
                  seq_recv;
 
+    unsigned int flags;
+
     int fd;
     char path[PATTY_AX25_SOCK_PATH_SIZE];
 
diff --git a/src/sock.c b/src/sock.c
index 7a0f3fb..080e65f 100644
--- a/src/sock.c
+++ b/src/sock.c
@@ -123,6 +123,7 @@ void patty_ax25_sock_reset(patty_ax25_sock *sock) {
     sock->n_maxlen        = 0;
     sock->n_retry         = 0;
     sock->n_window        = 0;
+    sock->flags           = 0;
     sock->seq_send        = 0;
     sock->seq_recv        = 0;
 }