diff --git a/bin/day2407.ml b/bin/day2407.ml
index d4ab0cf..3200b8f 100644
--- a/bin/day2407.ml
+++ b/bin/day2407.ml
@@ -35,8 +35,8 @@ let is_valid_target tgt nums ops =
     | [] -> List.exists (( = ) 0) tgts
     | h :: t ->
         impl
-          (List.map (fun tgt -> List.map (fun op -> op tgt h) ops) tgts
-          |> List.concat |> List.filter_map Fun.id)
+          (List.map (fun tgt -> List.filter_map (fun op -> op tgt h) ops) tgts
+          |> List.concat)
           t
   in
   impl [ tgt ] nums