diff --git a/hptp-recv/src/main.rs b/hptp-recv/src/main.rs
index 826047c..819f809 100644
--- a/hptp-recv/src/main.rs
+++ b/hptp-recv/src/main.rs
@@ -131,7 +131,6 @@ where
 
     const DELAY_MS: u64 = 1000;
     let mut deadline = Instant::now();
-    let mut to_send = vec![];
 
     loop {
         let timer = tokio::time::delay_until(deadline);
@@ -169,14 +168,10 @@ where
             }
         };
 
-        {
-            let idxs = sink.ack_idxs();
+        let num_acks = if sink.is_file_complete() { 8 } else { 1 };
+        for _ in 0..num_acks {
             log.debug_msg(format!("send acks {:?}", idxs)).await;
-            to_send.push(DownMsg::Ack { idxs: idxs.clone() });
-            to_send.push(DownMsg::Ack { idxs });
-        }
-
-        for m in to_send.drain(..) {
+            let m = DownMsg::Ack { idxs: sink.ack_idxs() };
             match peer.send(m).await {
                 Ok(()) => (),
                 Err(hptp::peer::SendError::NoTarget) => log.debug_msg("no target").await,