diff --git a/helpers/mirror.moon b/helpers/mirror.moon
index 4e431bf..a8703c0 100644
--- a/helpers/mirror.moon
+++ b/helpers/mirror.moon
@@ -65,7 +65,7 @@ update_manifest_on_disk = (server, dest, force=false) ->
 
           tmp_fname = "#{fname}.tmp"
 
-          http.request {
+          res, status = http.request {
             :url
             sink: ltn12.sink.file io.open tmp_fname, "w"
             headers: {
@@ -73,6 +73,12 @@ update_manifest_on_disk = (server, dest, force=false) ->
             }
           }
 
+          if (not res) or (type(status) == "number" and status >= 400)
+            seen_files[fname] = nil
+            os.execute "rm '#{tmp_fname}'"
+            print "failed"
+            continue
+
           os.execute "mv '#{tmp_fname}' #{fname}"
           print "done"