diff --git a/src/bin_proxy_server/main_proxy_server.ml b/src/bin_proxy_server/main_proxy_server.ml
index 47b4418312eaeed5f13bc7fc73c6f6ae585048f0..7bb2f8cbd1996276a661cd9e2ad02244a26356d9 100644
--- a/src/bin_proxy_server/main_proxy_server.ml
+++ b/src/bin_proxy_server/main_proxy_server.ml
@@ -32,7 +32,7 @@ let config : string option Term.t =
   let doc =
     "The configuration file. Fields (see corresponding options): endpoint \
      (string), rpc_addr (string), rpc_tls (string), sym_block_caching_time \
-     (int), and data_dir (string)."
+     (Ptime.span), and data_dir (string)."
   in
   let docv = "CONFIG" in
   Arg.(value & opt (some string) None & info ["c"; "config"] ~docv ~doc)
@@ -70,7 +70,7 @@ let data_dir : string option Term.t =
   let docv = "DATA_DIR" in
   Arg.(value & opt (some string) None & info ["d"; "data-dir"] ~docv ~doc)
 
-let sym_block_caching_time : int option Term.t =
+let sym_block_caching_time : Ptime.span option Term.t =
   let doc =
     "The duration (in seconds) during which data for a symbolic block \
      identifier (like head) is kept. Smaller values increase the endpoint's \
@@ -79,7 +79,7 @@ let sym_block_caching_time : int option Term.t =
      this value)."
   in
   let docv = "SYM_BLOCK_CACHING_TIME" in
-  Arg.(value & opt (some int) None & info ["sym-block-caching-time"] ~docv ~doc)
+  Arg.(value & opt (some Ptime.span conv) None & info ["sym-block-caching-time"] ~docv ~doc)
 
 let load_config_from_file (config_file : string) =
   let open Lwt_result_syntax in
diff --git a/src/lib_proxy/proxy_services.ml b/src/lib_proxy/proxy_services.ml
index 00e4fcdc6f9c6dc29283b7a0ff30e4cb34219045..06f69a042390b98689c4e4edbc0c185bc7f6e7d7 100644
--- a/src/lib_proxy/proxy_services.ml
+++ b/src/lib_proxy/proxy_services.ml
@@ -118,7 +118,7 @@ type mode =
   | Proxy_client
   | Proxy_server of {
       sleep : float -> unit Lwt.t;
-      sym_block_caching_time : int option;
+      sym_block_caching_time : Ptime.span option;
       on_disk_proxy_builder :
         (Context_hash.t -> Proxy_delegate.t tzresult Lwt.t) option;
     }
@@ -191,7 +191,7 @@ let schedule_clearing (printer : Tezos_client_base.Client_context.printer)
       let* time_between_blocks =
         match sym_block_caching_time with
         | Some sym_block_caching_time ->
-            Lwt.return @@ Int.to_float sym_block_caching_time
+            Lwt.return @@ Ptime.Span.to_float_s sym_block_caching_time
         | None -> (
             let (module Proxy_environment) = proxy_env in
             let* ro =
diff --git a/src/lib_proxy/proxy_services.mli b/src/lib_proxy/proxy_services.mli
index 566aab94694ece25df15012780456d818e127c68..6c893c59d71e743ec8981410d03347fad1498fb1 100644
--- a/src/lib_proxy/proxy_services.mli
+++ b/src/lib_proxy/proxy_services.mli
@@ -40,7 +40,7 @@ type mode =
   | Proxy_client  (** [tezos-client --mode proxy] is running *)
   | Proxy_server of {
       sleep : float -> unit Lwt.t;
-      sym_block_caching_time : int option;
+      sym_block_caching_time : Ptime.span option;
       on_disk_proxy_builder :
         (Context_hash.t -> Proxy_delegate.t tzresult Lwt.t) option;
     }