--- Gnu-Mach/i386/i386at/lpr.c	2020/09/02 04:53:37	1.1.1.4
+++ Gnu-Mach/i386/i386at/lpr.c	2020/09/02 04:55:39	1.1.1.5
@@ -232,7 +232,7 @@ void lprstart(struct tty *tp)
 	spl_t s = spltty();
 	u_short addr = (natural_t) tp->t_addr;
 	int status = inb(STATUS(addr));
-	char nch;
+	int nch;
 
 	if (tp->t_state & (TS_TIMEOUT|TS_TTSTOP|TS_BUSY)) {
 		splx(s);
@@ -253,6 +253,10 @@ void lprstart(struct tty *tp)
 		return;
 	}
 	nch = getc(&tp->t_outq);
+	if (nch == -1) {
+		splx(s);
+		return;
+	}
 	if ((tp->t_flags & LITOUT) == 0 && (nch & 0200)) {
 		timeout((timer_func_t *)ttrstrt, (char *)tp, (nch & 0x7f) + 6);
 		tp->t_state |= TS_TIMEOUT;