diff --git a/pmtiles/makesync.go b/pmtiles/makesync.go
index 70ec288..bab39a0 100644
--- a/pmtiles/makesync.go
+++ b/pmtiles/makesync.go
@@ -81,6 +81,8 @@ func DeserializesyncBlocks(num_blocks int, reader *bufio.Reader) []SyncBlock {
 }
 
 // measure the number of "missing blocks"
+// can further delta encode the length
+// what to do about extra blocks at the end
 func Makesync(logger *log.Logger, cli_version string, file string, block_size_kb int, checksum string) error {
 	ctx := context.Background()
 	start := time.Now()