diff --git a/sys/kern/tty_ttydisc.c b/sys/kern/tty_ttydisc.c
--- a/sys/kern/tty_ttydisc.c
+++ b/sys/kern/tty_ttydisc.c
@@ -822,7 +822,9 @@
 				/* Loop back through inq until we hit the
 				 * leading byte. */
 				while (CTL_UTF8_CONT(c) && nb < UTF8_STACKBUF) {
-					ttyinq_peekchar(&tp->t_inq, &c, &quote);
+					/* Check if we've reached the beginning of the line. */
+					if(ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
+						break;
 					ttyinq_unputchar(&tp->t_inq);
 					bytes[curidx] = c;
 					curidx--;