diff --git a/src/stdune/temp.ml b/src/stdune/temp.ml
index 7f1c7a231424..e4e18eb5c12f 100644
--- a/src/stdune/temp.ml
+++ b/src/stdune/temp.ml
@@ -85,7 +85,10 @@ let clear_dir dir =
   let remove_from_set ~set =
     set :=
       Path.Set.filter !set ~f:(fun f ->
-          (not (Path.equal f dir)) && Path.is_descendant ~of_:dir f)
+          let removed =
+            (not (Path.equal f dir)) && Path.is_descendant ~of_:dir f
+          in
+          not removed)
   in
   remove_from_set ~set:tmp_files;
   remove_from_set ~set:tmp_dirs