diff --git a/server/src/crate_server/user_backfill.gleam b/server/src/crate_server/user_backfill.gleam
index 64f9740..4a7c4dc 100644
--- a/server/src/crate_server/user_backfill.gleam
+++ b/server/src/crate_server/user_backfill.gleam
@@ -126,10 +126,8 @@ fn backfill_follows(
         Ok(Nil) -> index.seen.mark_seen(user.did)
         Error(_) -> Nil
       }
-    False -> Nil
-  }
-  case complete {
-    True -> Nil
+    // A truncated run cannot replace: the rows it did not see would be
+    // deleted. It adds what it has and leaves the did unseen.
     False -> rows |> list.each(index.edges.upsert)
   }
   list.length(rows)