diff --git a/src/libstore/path-info.hh b/src/libstore/path-info.hh
index 663d94540..35aced472 100644
--- a/src/libstore/path-info.hh
+++ b/src/libstore/path-info.hh
@@ -29,6 +29,7 @@ struct ValidPathInfo
 {
     StorePath path;
     std::optional<StorePath> deriver;
+    // TODO document this
     Hash narHash;
     StorePathSet references;
     time_t registrationTime = 0;