diff --git a/net/slirp.c b/net/slirp.c
index f98425e..ec07f66 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -704,8 +704,8 @@
              CONFIG_SMBD_COMMAND, s->smb_dir, smb_conf);
     g_free(smb_conf);
 
-    if (slirp_add_exec(s->slirp, NULL, smb_cmdline, &vserver_addr, 139) < 0 ||
-        slirp_add_exec(s->slirp, NULL, smb_cmdline, &vserver_addr, 445) < 0) {
+    if (slirp_add_exec(s->slirp, smb_cmdline, &vserver_addr, 139) < 0 ||
+        slirp_add_exec(s->slirp, smb_cmdline, &vserver_addr, 445) < 0) {
         slirp_smb_cleanup(s);
         g_free(smb_cmdline);
         error_setg(errp, "Conflicting/invalid smbserver address");
@@ -736,6 +736,11 @@
     slirp_socket_recv(fwd->slirp, fwd->server, fwd->port, buf, size);
 }
 
+static int guestfwd_write(const void *buf, size_t len, void *chr)
+{
+    return qemu_chr_fe_write_all(chr, buf, len);
+}
+
 static int slirp_guestfwd(SlirpState *s, const char *config_str, Error **errp)
 {
     struct in_addr server = { .s_addr = 0 };
@@ -769,7 +774,7 @@
     snprintf(buf, sizeof(buf), "guestfwd.tcp.%d", port);
 
     if ((strlen(p) > 4) && !strncmp(p, "cmd:", 4)) {
-        if (slirp_add_exec(s->slirp, NULL, &p[4], &server, port) < 0) {
+        if (slirp_add_exec(s->slirp, &p[4], &server, port) < 0) {
             error_setg(errp, "Conflicting/invalid host:port in guest "
                        "forwarding rule '%s'", config_str);
             return -1;
@@ -796,7 +801,8 @@
             return -1;
         }
 
-        if (slirp_add_exec(s->slirp, &fwd->hd, NULL, &server, port) < 0) {
+        if (slirp_add_guestfwd(s->slirp, guestfwd_write, &fwd->hd,
+                               &server, port) < 0) {
             error_setg(errp, "Conflicting/invalid host:port in guest "
                        "forwarding rule '%s'", config_str);
             g_free(fwd);