diff --git a/stand/libsa/tftp.c b/stand/libsa/tftp.c
--- a/stand/libsa/tftp.c
+++ b/stand/libsa/tftp.c
@@ -114,6 +114,8 @@
 	unsigned long	tftp_tsize;
 	void		*pkt;
 	struct tftphdr	*tftp_hdr;
+	char		*tftp_cache;
+	bool		lastacksent;
 };
 
 struct tftprecv_extra {
@@ -378,6 +380,7 @@
 			if (res < h->tftp_blksize) {
 				h->islastblock = 1;	/* very short file */
 				tftp_sendack(h, h->currblock);
+				h->lastacksent = true;
 			}
 			return (0);
 		}
@@ -594,7 +597,8 @@
 	struct tftp_handle *tftpfile;
 	tftpfile = f->f_fsdata;
 
-	/* let it time out ... */
+	if (tftpfile->lastacksent == false)
+		tftp_senderr(tftpfile, 0, "No error: file closed");
 
 	if (tftpfile) {
 		free(tftpfile->path);