diff --git a/server.c b/server.c
index ab18f473..822c2751 100644
--- a/server.c
+++ b/server.c
@@ -4850,7 +4850,8 @@ handle_tcp_writing(int fd, short event, void* arg)
 		}
 
 #ifdef HAVE_WRITEV
-		sent -= sizeof(n_tcplen);
+		/* The number of bytes transmitted for the message content. */
+		sent = data->bytes_transmitted - sizeof(n_tcplen);
 		/* handle potential 'packet done' code */
 		goto packet_could_be_done;
 #endif
diff --git a/xfrd-tcp.c b/xfrd-tcp.c
index acea5e2d..5f3abb51 100644
--- a/xfrd-tcp.c
+++ b/xfrd-tcp.c
@@ -1252,8 +1252,8 @@ int conn_write(struct xfrd_tcp* tcp)
 		}
 
 		tcp->total_bytes += sent;
-		if(sent > (ssize_t)sizeof(tcp->msglen))
-			buffer_skip(tcp->packet, sent-sizeof(tcp->msglen));
+		if(tcp->total_bytes > (ssize_t)sizeof(tcp->msglen))
+			buffer_skip(tcp->packet, tcp->total_bytes-sizeof(tcp->msglen));
 		if(tcp->total_bytes < sizeof(tcp->msglen)) {
 			/* incomplete write, resume later */
 			return 0;
-- 
2.54.0