diff --git a/src/proto_alpha/lib_protocol/alpha_context.mli b/src/proto_alpha/lib_protocol/alpha_context.mli
index 522186053bb077d4779d8a07c68903348175ac51..6fcfd1635a1c349e0f0b419aeaf9c2c2a33acc35 100644
--- a/src/proto_alpha/lib_protocol/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/alpha_context.mli
@@ -2266,6 +2266,11 @@ module Delegate : sig
       Signature.Public_key_hash.t ->
       Staking_parameters_repr.t ->
       context tzresult Lwt.t
+
+    val of_delegate :
+      context ->
+      Signature.Public_key_hash.t ->
+      Staking_parameters_repr.t tzresult Lwt.t
   end
 end
 
diff --git a/src/proto_alpha/lib_protocol/apply.ml b/src/proto_alpha/lib_protocol/apply.ml
index b94378349bddecf722905be46b433c742967552b..6224b6fd98930cf27c488eb77321b6c796f8e1dd 100644
--- a/src/proto_alpha/lib_protocol/apply.ml
+++ b/src/proto_alpha/lib_protocol/apply.ml
@@ -44,6 +44,7 @@ type error +=
   | Invalid_sender of Destination.t
   | Invalid_self_transaction_destination
   | Staking_for_nondelegate_while_costaking_disabled
+  | Staking_to_delegate_that_refuses_costaking
   | Invalid_nonzero_transaction_amount of Tez.t
   | Invalid_unstake_request_amount of {requested_amount : Z.t}
   | Invalid_staking_parameters_sender
@@ -239,6 +240,23 @@ let () =
     (function
       | Staking_for_nondelegate_while_costaking_disabled -> Some () | _ -> None)
     (fun () -> Staking_for_nondelegate_while_costaking_disabled) ;
+  let staking_to_delegate_that_refuses_costaking_description =
+    "The delegate currently does not accept staking operations from sources \
+     other than itself: its `staking_over_baking_limit` parameter is set to 0."
+  in
+  register_error_kind
+    `Permanent
+    ~id:"operations.staking_to_delegate_that_refuses_costaking"
+    ~title:"Staking to delegate that does not accept external staking"
+    ~description:staking_to_delegate_that_refuses_costaking_description
+    ~pp:(fun ppf () ->
+      Format.pp_print_string
+        ppf
+        staking_to_delegate_that_refuses_costaking_description)
+    Data_encoding.unit
+    (function
+      | Staking_to_delegate_that_refuses_costaking -> Some () | _ -> None)
+    (fun () -> Staking_to_delegate_that_refuses_costaking) ;
   register_error_kind
     `Permanent
     ~id:"operations.invalid_nonzero_transaction_amount"
@@ -353,6 +371,16 @@ let apply_stake ~ctxt ~sender ~amount ~destination ~before_operation =
       let*? () =
         error_unless allowed Staking_for_nondelegate_while_costaking_disabled
       in
+      let* {staking_over_baking_limit; _} =
+        Delegate.Staking_parameters.of_delegate ctxt delegate
+      in
+      let forbidden =
+        Signature.Public_key_hash.(delegate <> sender)
+        && Compare.Int32.(staking_over_baking_limit = 0l)
+      in
+      let*? () =
+        error_when forbidden Staking_to_delegate_that_refuses_costaking
+      in
       let* ctxt, balance_updates =
         Staking.stake ctxt ~sender ~delegate amount
       in
diff --git a/src/proto_alpha/lib_protocol/delegate_staking_parameters.ml b/src/proto_alpha/lib_protocol/delegate_staking_parameters.ml
index 7982a66ac465f746bfb18f6095e64859a5c47c18..2a933b5814dd01dcdb80f186e965f0bfeab4b4cf 100644
--- a/src/proto_alpha/lib_protocol/delegate_staking_parameters.ml
+++ b/src/proto_alpha/lib_protocol/delegate_staking_parameters.ml
@@ -24,7 +24,15 @@
 (*****************************************************************************)
 
 let of_delegate ctxt delegate =
-  Storage.Contract.Staking_parameters.get ctxt (Contract_repr.Implicit delegate)
+  let open Lwt_result_syntax in
+  let* t =
+    Storage.Contract.Staking_parameters.find
+      ctxt
+      (Contract_repr.Implicit delegate)
+  in
+  match t with
+  | None -> return Staking_parameters_repr.default
+  | Some t -> return t
 
 let raw_pending_updates ctxt delegate =
   Storage.Contract.Pending_staking_parameters.bindings
diff --git a/src/proto_alpha/lib_protocol/staking_parameters_repr.ml b/src/proto_alpha/lib_protocol/staking_parameters_repr.ml
index 5393f26bfb9bc3de2ff550e07a230f630ca158ed..e2080c48283f8566dc6d8e647acd28da3bf8820b 100644
--- a/src/proto_alpha/lib_protocol/staking_parameters_repr.ml
+++ b/src/proto_alpha/lib_protocol/staking_parameters_repr.ml
@@ -32,6 +32,8 @@ let maximum_baking_over_staking_edge =
   (* max is 1 expressed in portions of 1_000_000_000 *)
   1_000_000_000l
 
+let default = {staking_over_baking_limit = 0l; baking_over_staking_edge = 0l}
+
 type error += Invalid_staking_parameters
 
 let () =
diff --git a/src/proto_alpha/lib_protocol/staking_parameters_repr.mli b/src/proto_alpha/lib_protocol/staking_parameters_repr.mli
index 1e371c973c080b10717339cdf661d1da16696d54..1c47f99de79907424e07b8f1a913bd08758500cf 100644
--- a/src/proto_alpha/lib_protocol/staking_parameters_repr.mli
+++ b/src/proto_alpha/lib_protocol/staking_parameters_repr.mli
@@ -28,6 +28,9 @@ type t = private {
   baking_over_staking_edge : int32; (* as a portion of 1_000_000_000 *)
 }
 
+(** Value used when unset *)
+val default : t
+
 type error += Invalid_staking_parameters
 
 val make :