diff --git a/libexec/tftpd/tests/functional.c b/libexec/tftpd/tests/functional.c
--- a/libexec/tftpd/tests/functional.c
+++ b/libexec/tftpd/tests/functional.c
@@ -323,6 +323,7 @@
 {
 	int client_s, server_s, pid, argv_idx;
 	char execname[] = "/usr/libexec/tftpd";
+	char b_flag_str[] = "-b";
 	char s_flag_str[] = "-s";
 	char w_flag_str[] = "-w";
 	char pwd[MAXPATHLEN];
@@ -382,6 +383,7 @@
 		bzero(argv, sizeof(argv));
 		argv[0] = execname;
 		argv_idx = 1;
+		argv[argv_idx++] = b_flag_str;
 		if (w_flag)
 			argv[argv_idx++] = w_flag_str;
 		if (s_flag)
diff --git a/libexec/tftpd/tftpd.8 b/libexec/tftpd/tftpd.8
--- a/libexec/tftpd/tftpd.8
+++ b/libexec/tftpd/tftpd.8
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd May 8, 2024
+.Dd November 3, 2024
 .Dt TFTPD 8
 .Os
 .Sh NAME
@@ -33,7 +33,7 @@
 .Nd Internet Trivial File Transfer Protocol server
 .Sh SYNOPSIS
 .Nm tftpd
-.Op Fl CcdlnoSw
+.Op Fl bCcdlnoSw
 .Op Fl F Ar strftime-format
 .Op Fl s Ar directory
 .Op Fl U Ar umask
@@ -119,6 +119,16 @@
 .Pp
 The options are:
 .Bl -tag -width Ds
+.It Fl b
+By default,
+.Nm
+expects an initial message to be available on its input socket.
+If no data is available, the server exits immediately.
+If
+.Fl b
+is specified,
+.Nm
+will block waiting for the initial message.
 .It Fl c
 Changes the default root directory of a connecting host via
 .Xr chroot 2
diff --git a/libexec/tftpd/tftpd.c b/libexec/tftpd/tftpd.c
--- a/libexec/tftpd/tftpd.c
+++ b/libexec/tftpd/tftpd.c
@@ -121,15 +121,18 @@
 	struct passwd	*nobody;
 	const char	*chuser = "nobody";
 	char		recvbuffer[MAXPKTSIZE];
-	int		allow_ro = 1, allow_wo = 1, on = 1;
+	int		allow_ro = 1, allow_wo = 1, block = 0, on = 1;
 	pid_t		pid;
 
 	tzset();			/* syslog in localtime */
 	acting_as_client = 0;
 
 	tftp_openlog("tftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
-	while ((ch = getopt(argc, argv, "cCd::F:lnoOp:s:Su:U:wW")) != -1) {
+	while ((ch = getopt(argc, argv, "bcCd::F:lnoOp:s:Su:U:wW")) != -1) {
 		switch (ch) {
+		case 'b':
+			block = 1;
+			break;
 		case 'c':
 			ipchroot = 1;
 			break;
@@ -213,14 +216,9 @@
 
 	umask(mask);
 
-	if (ioctl(0, FIONBIO, &on) < 0) {
-		tftp_log(LOG_ERR, "ioctl(FIONBIO): %s", strerror(errno));
-		exit(1);
-	}
-
 	/* Find out who we are talking to and what we are going to do */
 	peerlen = sizeof(peer_sock);
-	n = recvfrom(0, recvbuffer, MAXPKTSIZE, 0,
+	n = recvfrom(0, recvbuffer, MAXPKTSIZE, block ? 0 : MSG_DONTWAIT,
 	    (struct sockaddr *)&peer_sock, &peerlen);
 	if (n < 0) {
 		tftp_log(LOG_ERR, "recvfrom: %s", strerror(errno));
@@ -234,6 +232,11 @@
 		exit(1);
 	}
 
+	if (ioctl(0, FIONBIO, &on) < 0) {
+		tftp_log(LOG_ERR, "ioctl(FIONBIO): %s", strerror(errno));
+		exit(1);
+	}
+
 	/*
 	 * Now that we have read the message out of the UDP
 	 * socket, we fork and exit.  Thus, inetd will go back