diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index ef3326cd6..6079eae7b 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -402,6 +402,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             logger->startWork();
             auto pathInfo = [&]() {
                 // NB: FramedSource must be out of scope before logger->stopWork();
+                // FIXME: this means that if there is an error
+                // half-way through, the client will keep sending
+                // data, since we haven't sent it the error yet.
                 auto [contentAddressMethod, hashAlgo] = ContentAddressMethod::parseWithAlgo(camStr);
                 FramedSource source(conn.from);
                 FileSerialisationMethod dumpMethod;