diff --git a/CHANGES.md b/CHANGES.md
index 302d33a373b..c318f670028 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,9 @@
 Unreleased
 ----------
 
+- Allow `$ dune utop` to load libraries defined in data only directories
+  defined using `(subdir ..)` (#6631, @rgrinberg)
+
 - Format dune files when they are named `dune-file`. This occurs when we enable
   the alternative file names project option. (#6566, @rgrinberg)
 
diff --git a/src/dune_rules/utop.ml b/src/dune_rules/utop.ml
index d6224540f05..3ce0f1f6b31 100644
--- a/src/dune_rules/utop.ml
+++ b/src/dune_rules/utop.ml
@@ -38,9 +38,7 @@ let libs_and_ppx_under_dir sctx ~db ~dir =
   | None -> Memo.return ([], [])
   | Some dir ->
     let+ libs, pps =
-      Source_tree_map_reduce.map_reduce
-        dir (* TODO this is wrong under [(subdir ..)] *)
-        ~traverse:{ data_only = false; vendored = true; normal = true }
+      Source_tree_map_reduce.map_reduce dir ~traverse:Sub_dirs.Status.Set.all
         ~f:(fun dir ->
           let dir =
             Path.Build.append_source (Super_context.context sctx).build_dir
diff --git a/test/blackbox-tests/test-cases/utop/lib-under-subdir.t b/test/blackbox-tests/test-cases/utop/lib-under-subdir.t
index 0575410332b..247c8b4bb14 100644
--- a/test/blackbox-tests/test-cases/utop/lib-under-subdir.t
+++ b/test/blackbox-tests/test-cases/utop/lib-under-subdir.t
@@ -22,8 +22,4 @@ dune utop should read libraries in (subdir ..)
   > EOF
 
   $ dune utop . -- foo.ml
-  File "foo.ml", line 1, characters 0-9:
-  1 | Foolib.hw ()
-      ^^^^^^^^^
-  Error: Unbound module Foolib
-  [2]
+  foolib