diff --git a/hw/serial.c b/hw/serial.c
index 9102edb..0b1550b 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -327,7 +327,7 @@ static void serial_xmit(void *opaque)
         /* in loopback mode, say that we just received a char */
         serial_receive1(s, &s->tsr, 1);
     } else if (qemu_chr_write(s->chr, &s->tsr, 1) != 1) {
-        if ((s->tsr_retry > 0) && (s->tsr_retry <= MAX_XMIT_RETRY)) {
+        if ((s->tsr_retry >= 0) && (s->tsr_retry <= MAX_XMIT_RETRY)) {
             s->tsr_retry++;
             qemu_mod_timer(s->transmit_timer,  new_xmit_ts + s->char_transmit_time);
             return;