diff --git a/src/timestamp.ml b/src/timestamp.ml
index a63d74d1..7dfc68ec 100644
--- a/src/timestamp.ml
+++ b/src/timestamp.ml
@@ -1,3 +1,4 @@
+module T = struct
 type t = Ptime.t
 type span = Ptime.span
 
@@ -20,8 +21,8 @@ let of_int_s s = Ptime.of_span @@ span_of_int_s s
 let of_int64_us us = Ptime.of_span @@ span_of_int64_us us
 let to_int_s t = Ptime.Span.to_int_s (Ptime.to_span t)
 
-let to_int64_us span =
-  match to_int_s span with
+let to_int64_us t =
+  match to_int_s t with
   | None -> None
   | Some s ->
       let us = Int64.(mul (of_int s) 1_000_000_L) in
@@ -31,6 +32,24 @@ let now () = Ptime_clock.now ()
 let add_span t span = Ptime.add_span t span
 let sub_span t span = Ptime.sub_span t span
 let diff a b = Ptime.diff a b
+end
+
+type t = | T_uint64_us of int64 | Never
+
+let to_uint64 =
+  function | T_uint64_us us -> us | Never -> (* never/forever case :=  uint64_max *)
+    -1L
+
+let of_uint64 us =
+  if us = -1L then Never else T_uint64_us us
+
+let now () =
+  let opt = T.to_int64_us @@
+  Ptime_clock.now () in
+  match opt with
+  | None -> Fmt.failure "invalid Ptime_clock.now value"
+  | Some us ->
+
 (*
 (* microseconds since the UNIX Epoch, or "never" if None *)
 let jsont =