diff --git a/examples/ax25dump.c b/examples/ax25dump.c
index fd309a4..e762de6 100644
--- a/examples/ax25dump.c
+++ b/examples/ax25dump.c
@@ -33,8 +33,7 @@ int main(int argc, char **argv) {
     patty_ax25_call_setsockopt_if ifreq;
 
     int fd,
-        sock,
-        pty;
+        sock;
 
     patty_ax25_addr peer;
     char path[PATTY_AX25_SOCK_PATH_SIZE];
@@ -42,6 +41,8 @@ int main(int argc, char **argv) {
     uint8_t buf[4096];
     ssize_t readlen;
 
+    patty_kiss_tnc *raw;
+
     if (argc != 2) {
         usage(argc, argv, "No patty socket provided");
     }
@@ -79,14 +80,14 @@ int main(int argc, char **argv) {
         goto error_call_setsockopt;
     }
 
-    if ((pty = open(path, O_RDWR)) < 0) {
+    if ((raw = patty_kiss_tnc_new(path)) == NULL) {
         fprintf(stderr, "%s: %s: %s: %s\n",
-            argv[0], path, "open()", strerror(errno));
+            argv[0], path, "patty_kiss_tnc_new()", strerror(errno));
 
-        goto error_open_pty;
+        goto error_kiss_tnc_new;
     }
 
-    while ((readlen = read(pty, buf, sizeof(buf))) > 0) {
+    while ((readlen = patty_kiss_tnc_recv(raw, buf, sizeof(buf), NULL)) > 0) {
         patty_ax25_frame frame;
 
         if (patty_ax25_frame_decode(&frame, PATTY_AX25_FRAME_NORMAL, buf, readlen) < 0) {
@@ -104,7 +105,7 @@ int main(int argc, char **argv) {
         }
     }
 
-    close(pty);
+    patty_kiss_tnc_destroy(raw);
 
     patty_ax25_call_close(fd, sock);
 
@@ -114,7 +115,9 @@ int main(int argc, char **argv) {
 
 error_print_frame:
 error_ax25_frame_decode:
-error_open_pty:
+    patty_kiss_tnc_destroy(raw);
+
+error_kiss_tnc_new:
     patty_ax25_call_close(fd, sock);
 
 error_call_setsockopt:
diff --git a/src/if.c b/src/if.c
index c52fa00..46e67b0 100644
--- a/src/if.c
+++ b/src/if.c
@@ -273,15 +273,21 @@ error_ntop:
 
 int patty_ax25_if_promisc_add(patty_ax25_if *iface,
                               int fd) {
+    patty_kiss_tnc *tnc;
+
     if (patty_dict_get(iface->promisc_fds, (uint32_t)fd)) {
         errno = EEXIST;
 
         goto error_exists;
     }
 
+    if ((tnc = patty_kiss_tnc_new_fd(fd)) == NULL) {
+        goto error_kiss_tnc_new_fd;
+    }
+
     if (patty_dict_set(iface->promisc_fds,
                        (uint32_t)fd,
-                       NULL + fd) == NULL) {
+                       tnc) == NULL) {
         errno = ENOMEM;
 
         goto error_dict_set;
@@ -290,20 +296,26 @@ int patty_ax25_if_promisc_add(patty_ax25_if *iface,
     return 0;
 
 error_dict_set:
+    patty_kiss_tnc_destroy(tnc);
+
+error_kiss_tnc_new_fd:
 error_exists:
     return -1;
 }
 
 int patty_ax25_if_promisc_delete(patty_ax25_if *iface,
                                  int fd) {
-    if (patty_dict_delete(iface->promisc_fds,
-                          (uint32_t)fd) < 0) {
+    patty_kiss_tnc *tnc;
+
+    if ((tnc = patty_dict_get(iface->promisc_fds, (uint32_t)fd)) == NULL) {
         errno = ENOENT;
 
         goto error_notfound;
     }
 
-    return 0;
+    patty_kiss_tnc_destroy(tnc);
+
+    return patty_dict_delete(iface->promisc_fds, (uint32_t)fd);
 
 error_notfound:
     return -1;
@@ -318,17 +330,10 @@ struct promisc_frame {
 static int handle_promisc_frame(uint32_t key,
                                 void *value,
                                 void *ctx) {
-    int fd = (int)key;
+    patty_kiss_tnc *tnc = value;
     struct promisc_frame *frame = ctx;
 
-    if (write(fd, frame->buf, frame->len) < 0) {
-        goto error_write;
-    }
-
-    return tcdrain(fd);
-
-error_write:
-    return -1;
+    return patty_kiss_tnc_send(tnc, frame->buf, frame->len, 0);
 }
 
 ssize_t patty_ax25_if_recv(patty_ax25_if *iface,
diff --git a/src/kiss.c b/src/kiss.c
index b580522..cb4d895 100644
--- a/src/kiss.c
+++ b/src/kiss.c
@@ -183,7 +183,9 @@ ssize_t patty_kiss_tnc_recv(patty_kiss_tnc *tnc,
                 goto error_io;
             }
 
-            *port = PATTY_KISS_COMMAND_PORT(c);
+            if (port) {
+                *port = PATTY_KISS_COMMAND_PORT(c);
+            }
 
             flags |= KISS_COMMAND;