diff --git a/Basis/ContractedShellPair.ml b/Basis/ContractedShellPair.ml
index e9dbd4b..16392da 100644
--- a/Basis/ContractedShellPair.ml
+++ b/Basis/ContractedShellPair.ml
@@ -121,13 +121,13 @@ let cmp a b =
 *)
 let of_contracted_shell_array ?(cutoff=Constants.epsilon) basis =
   let rec loop accu = function
-  | [] -> List.rev accu
+  | [] -> accu
   | (s_a :: rest) as l ->
     let new_accu = 
       (List.map (fun s_b -> make ~cutoff s_a s_b) l) :: accu
     in loop new_accu rest
   in
-  loop [] (Array.to_list basis)
+  loop [] (List.rev (Array.to_list basis))
   |> List.concat
   |> list_some