diff --git a/src/client/embedded/genesis/client_proto_main.ml b/src/client/embedded/genesis/client_proto_main.ml
index 14c325bfe..7f9c17d1b 100644
--- a/src/client/embedded/genesis/client_proto_main.ml
+++ b/src/client/embedded/genesis/client_proto_main.ml
@@ -25,9 +25,9 @@ let forge_block
     Services.Forge.block block
     ((net_id, pred, timestamp, fitness), command)
 
-let mine cctxt block command fitness seckey =
+let mine cctxt ?timestamp block command fitness seckey =
   Client_blocks.get_block_info cctxt block >>= fun bi ->
-  forge_block cctxt block bi.net command fitness >>= fun blk ->
+  forge_block cctxt ?timestamp block bi.net command fitness >>= fun blk ->
   let signed_blk = Environment.Ed25519.Signature.append seckey blk in
   Client_node_rpcs.inject_block cctxt ~wait:true signed_blk >>=? fun hash ->
   cctxt.answer "Injected %a" Block_hash.pp_short hash >>= fun () ->
@@ -41,9 +41,14 @@ let handle_error cctxt = function
       cctxt.Client_commands.error "%s" "cannot continue"
 
 let commands () =
+  let timestamp = ref None in
+  let args =
+    [ "-timestamp",
+      Arg.String (fun t -> timestamp := Some (Time.of_notation_exn t)),
+      "Set the timestamp of the block (and initial time of the chain)" ] in
   let open Cli_entries in
   [
-    command ~desc: "Activate a protocol" begin
+    command ~args ~desc: "Activate a protocol" begin
       prefixes [ "activate" ; "protocol" ] @@
       param ~name:"version" ~desc:"Protocol version (b58check)"
         (fun _ p -> Lwt.return @@ Protocol_hash.of_b58check p) @@
@@ -57,12 +62,14 @@ let commands () =
       stop
     end
       (fun hash fitness seckey cctxt ->
+         let timestamp = !timestamp in
          let block = Client_config.block () in
          let fitness =
            Client_embedded_proto_alpha.Fitness_repr.from_int64 fitness in
-         mine cctxt block (Activate hash) fitness seckey >>= handle_error cctxt)
+         mine cctxt ?timestamp block (Activate hash) fitness seckey >>=
+         handle_error cctxt)
     ;
-    command ~desc: "Fork a test protocol" begin
+      command ~args ~desc: "Fork a test protocol" begin
       prefixes [ "fork" ; "test" ; "protocol" ] @@
       param ~name:"version" ~desc:"Protocol version (b58check)"
         (fun _ p -> Lwt.return (Protocol_hash.of_b58check p)) @@
@@ -77,10 +84,12 @@ let commands () =
         stop
     end
       (fun hash fitness seckey cctxt ->
+         let timestamp = !timestamp in
          let block = Client_config.block () in
          let fitness =
            Client_embedded_proto_alpha.Fitness_repr.from_int64 fitness in
-         mine cctxt block (Activate_testnet hash) fitness seckey >>= handle_error cctxt) ;
+         mine cctxt ?timestamp block (Activate_testnet hash) fitness seckey >>=
+         handle_error cctxt) ;
   ]
 
 let () =
diff --git a/src/client/embedded/genesis/client_proto_main.mli b/src/client/embedded/genesis/client_proto_main.mli
index c548f2bb8..451964484 100644
--- a/src/client/embedded/genesis/client_proto_main.mli
+++ b/src/client/embedded/genesis/client_proto_main.mli
@@ -9,6 +9,7 @@
 
 val mine:
   Client_commands.context ->
+  ?timestamp: Time.t ->
   Client_node_rpcs.Blocks.block ->
   Data.Command.t ->
   Fitness.fitness ->