diff --git a/PDP11/pdp11_kdp.c b/PDP11/pdp11_kdp.c
index 92d7a8eb..faaa107f 100644
--- a/PDP11/pdp11_kdp.c
+++ b/PDP11/pdp11_kdp.c
@@ -393,10 +393,11 @@ t_stat send_buffer(int dupindex)
 	{
 		r = send_packet(&dup_dev[dupindex], &kdp_ldsc[dupindex], d->txbuf, d->txbuflen);
 		d->txnext += d->txnow;
-		d->txnow = 0;
 		kmc_output = TRUE;
 	}
 
+	d->txnow = 0;
+
 	return r;
 }