diff --git a/src/secmod_eddsa.ml b/src/secmod_eddsa.ml
index bd46794a..5bdd9ca6 100644
--- a/src/secmod_eddsa.ml
+++ b/src/secmod_eddsa.ml
@@ -86,6 +86,7 @@ let get_key_dir_contents dir =
 let sort_keys l = List.sort (fun a b -> Absolute.compare a.t2 b.t2) l
 
 let split_in_periodes ~start ~end_ =
+  assert (start < end_);
   (* no overlap on first periode *)
   let t1 = start in
   let t2 = Absolute.add start Cfg.duration in
@@ -160,10 +161,9 @@ let init () =
   let now = Absolute.of_ptime (Ptime_clock.now ()) in
   let* () = check_periodes t.keys in
   let new_keys = gen_additional_keys_until_lookahead ~now t.keys in
-  let* () = list_iter write_key new_keys in
+  let+ () = list_iter write_key new_keys in
   let keys = sort_keys (t.keys @ new_keys) in
-  let t = { t with keys } in
-  Ok t
+  { t with keys }
 
 (* --- *)
 
@@ -189,8 +189,7 @@ let delete_key pub =
   let* k = find_key pub in
   let l = List.filter (fun k -> k.pub <> pub) t.keys in
   t.keys <- l;
-  let+ () = delete_key_file k in
-  ()
+  delete_key_file k
 
 let delete_outdated ~now =
   t.keys