diff --git a/src/proto_alpha/lib_baking/test/test_transaction.ml b/src/proto_alpha/lib_baking/test/test_transaction.ml
index ee9173f4b..bc4262eca 100644
--- a/src/proto_alpha/lib_baking/test/test_transaction.ml
+++ b/src/proto_alpha/lib_baking/test/test_transaction.ml
@@ -85,7 +85,7 @@ let run blkid ({ b1 ; b2 ; b3 ; _ } : Helpers.Account.bootstrap_accounts) =
     ~account
     ~destination:b3.contract
     ~amount:(tez 10L) () >>= fun result ->
-  Assert.inconsistent_pkh ~msg:__LOC__ result ;
+  Assert.inconsistent_public_key ~msg:__LOC__ result ;
 
   (* Try spending an originated contract without the manager's key. *)
   let account = { b1 with contract = spendable } in
diff --git a/src/proto_alpha/lib_protocol/src/bootstrap_storage.ml b/src/proto_alpha/lib_protocol/src/bootstrap_storage.ml
index 45ec8b7c2..703e95bfa 100644
--- a/src/proto_alpha/lib_protocol/src/bootstrap_storage.ml
+++ b/src/proto_alpha/lib_protocol/src/bootstrap_storage.ml
@@ -14,10 +14,13 @@ type account = {
 
 let init_account ctxt account =
   Storage.Public_key.init ctxt account.public_key_hash account.public_key >>=? fun ctxt ->
-  Contract_storage.credit
-    ctxt
-    (Contract_repr.implicit_contract account.public_key_hash)
+  let contract = Contract_repr.implicit_contract account.public_key_hash in
+  Contract_storage.credit ctxt contract
     Constants_repr.bootstrap_wealth >>=? fun ctxt ->
+  Contract_storage.update_manager_key ctxt contract
+    (Some account.public_key) >>=? fun (ctxt, _) ->
+  Contract_storage.set_delegate ctxt contract
+    (Some account.public_key_hash) >>=? fun ctxt ->
   return ctxt
 
 
diff --git a/src/proto_alpha/lib_protocol/src/contract_storage.ml b/src/proto_alpha/lib_protocol/src/contract_storage.ml
index f9a722a5f..a5628ca21 100644
--- a/src/proto_alpha/lib_protocol/src/contract_storage.ml
+++ b/src/proto_alpha/lib_protocol/src/contract_storage.ml
@@ -18,6 +18,7 @@ type error +=
   | Inconsistent_public_key of Ed25519.Public_key.t * Ed25519.Public_key.t (* `Permanent *)
   | Missing_public_key of Ed25519.Public_key_hash.t (* `Permanent *)
   | Failure of string (* `Permanent *)
+  | Unregistred_delegate of Ed25519.Public_key_hash.t (* `Permanent *)
 
 let () =
   register_error_kind
@@ -136,12 +137,12 @@ let () =
     ~id:"contract.manager.missing_public_key"
     ~title:"Missing public key"
     ~description:"The manager public key must be provided to execute the current operation"
-    ~pp:(fun ppf (k) ->
+    ~pp:(fun ppf k ->
         Format.fprintf ppf "The manager public key ( with hash %a ) is missing"
           Ed25519.Public_key_hash.pp k)
     Data_encoding.(obj1 (req "hash" Ed25519.Public_key_hash.encoding))
-    (function Missing_public_key (k) -> Some (k) | _ -> None)
-    (fun (k) -> Missing_public_key (k)) ;
+    (function Missing_public_key k -> Some k | _ -> None)
+    (fun k -> Missing_public_key k) ;
   register_error_kind
     `Permanent
     ~id:"contract.failure"
@@ -150,7 +151,18 @@ let () =
     ~pp:(fun ppf s -> Format.fprintf ppf "Contract_storage.Failure %S" s)
     Data_encoding.(obj1 (req "message" string))
     (function Failure s -> Some s | _ -> None)
-    (fun s -> Failure s)
+    (fun s -> Failure s) ;
+  register_error_kind
+    `Permanent
+    ~id:"contract.manager.unregistred_delegate"
+    ~title:"Unregistred delegate"
+    ~description:"A contract cannot be delegated to an unregistred delegate"
+    ~pp:(fun ppf (k) ->
+        Format.fprintf ppf "The delegate public key (with hash %a) is missing"
+          Ed25519.Public_key_hash.pp k)
+    Data_encoding.(obj1 (req "hash" Ed25519.Public_key_hash.encoding))
+    (function Unregistred_delegate (k) -> Some (k) | _ -> None)
+    (fun (k) -> Unregistred_delegate (k))
 
 let failwith msg = fail (Failure msg)
 
@@ -168,7 +180,12 @@ let create_base c contract
         Storage.Contract.Delegate.init c contract delegate
   end >>=? fun c ->
   Storage.Contract.Spendable.init c contract spendable >>=? fun c ->
-  Storage.Contract.Delegatable.init c contract delegatable >>=? fun c ->
+  begin
+    if delegatable then
+      Storage.Contract.Delegatable.add c contract
+    else
+      Lwt.return c
+  end >>= fun c ->
   Storage.Contract.Counter.init c contract counter >>=? fun c ->
   (match script with
    | Some ({ Script_repr.code ; storage }, (code_fees, storage_fees)) ->
@@ -189,8 +206,7 @@ let originate c nonce ~balance ~manager ?script ~delegate ~spendable ~delegatabl
 
 let create_implicit c manager ~balance =
   create_base c (Contract_repr.implicit_contract manager)
-    ~balance ~manager ~delegate:(Some manager)
-    ?script:None
+    ~balance ~manager ?script:None ~delegate:None
     ~spendable:true ~delegatable:false
 
 let delete c contract =
@@ -201,7 +217,7 @@ let delete c contract =
   Storage.Contract.Manager.delete c contract >>=? fun c ->
   Storage.Contract.Delegate.remove c contract >>= fun c ->
   Storage.Contract.Spendable.delete c contract >>=? fun c ->
-  Storage.Contract.Delegatable.delete c contract >>=? fun c ->
+  Storage.Contract.Delegatable.del c contract >>= fun c ->
   Storage.Contract.Counter.delete c contract >>=? fun c ->
   Storage.Contract.Code.remove c contract >>= fun c ->
   Storage.Contract.Storage.remove c contract >>= fun c ->
@@ -302,13 +318,11 @@ let get_balance c contract =
   | Some v -> return v
 
 let is_delegatable c contract =
-  Storage.Contract.Delegatable.get_option c contract >>=? function
-  | None -> begin
-      match Contract_repr.is_implicit contract with
-      | Some _ -> return false
-      | None -> failwith "is_delegatable"
-    end
-  | Some v -> return v
+  match Contract_repr.is_implicit contract with
+  | Some _ ->
+      return false
+  | None ->
+      Storage.Contract.Delegatable.mem c contract >>= return
 
 let is_spendable c contract =
   Storage.Contract.Spendable.get_option c contract >>=? function
@@ -320,17 +334,33 @@ let is_spendable c contract =
   | Some v -> return v
 
 let set_delegate c contract delegate =
-  (* A contract delegate can be set only if the contract is delegatable *)
-  is_delegatable c contract >>=? function
-  | false -> fail (Non_delegatable_contract contract)
-  | true ->
-      match delegate with
-      | None ->
-          Storage.Contract.Delegate.remove c contract >>= fun c ->
-          return c
-      | Some delegate ->
-          Storage.Contract.Delegate.init_set c contract delegate >>= fun c ->
-          return c
+  match delegate with
+  | None ->
+      Storage.Contract.Delegate.remove c contract >>= fun c ->
+      return c
+  | Some delegate ->
+      begin
+        Storage.Contract.Manager.get_option
+          c (Contract_repr.implicit_contract delegate) >>=? function
+        | None | Some (Manager_repr.Hash _) -> return false
+        | Some (Manager_repr.Public_key _) -> return true
+      end >>=? fun known_delegate ->
+      Storage.Contract.Delegate.mem
+        c (Contract_repr.implicit_contract delegate)
+      >>= fun registred_delegate ->
+      is_delegatable c contract >>=? fun delegatable ->
+      let self_delegation =
+        match Contract_repr.is_implicit contract with
+        | Some pkh -> Ed25519.Public_key_hash.equal pkh delegate
+        | None -> false in
+      if not known_delegate || not (registred_delegate || self_delegation) then
+        fail (Unregistred_delegate delegate)
+      else if not (delegatable || self_delegation) then
+        fail (Non_delegatable_contract contract)
+      else
+        Storage.Contract.Delegate.init_set c contract delegate >>= fun c ->
+        return c
+
 
 let code_and_storage_fee c contract =
   Storage.Contract.Code_fees.get_option c contract >>=? fun code_fees ->
@@ -375,8 +405,16 @@ let spend_from_script c contract amount =
         Roll_storage.Contract.remove_amount c contract amount
       else
         match Contract_repr.is_implicit contract with
-        | Some _ -> delete c contract
-        | None -> return c
+        | None -> return c (* don't delete originated contract. *)
+        | Some pkh ->
+            Storage.Contract.Delegate.get_option c contract >>=? function
+            | Some pkh' ->
+                (* Don't delete "delegate" contract *)
+                assert (Ed25519.Public_key_hash.equal pkh pkh') ;
+                return c
+            | None ->
+                (* Delete empty implicit contract *)
+                delete c contract
 
 let credit c contract amount =
   Storage.Contract.Balance.get_option c contract >>=? function
diff --git a/src/proto_alpha/lib_protocol/src/roll_storage.ml b/src/proto_alpha/lib_protocol/src/roll_storage.ml
index dabf7fc9a..60a6c0375 100644
--- a/src/proto_alpha/lib_protocol/src/roll_storage.ml
+++ b/src/proto_alpha/lib_protocol/src/roll_storage.ml
@@ -14,9 +14,7 @@ type error +=
   | No_roll_snapshot_for_cycle of Cycle_repr.t
 
 let get_contract_delegate c contract =
-  match Contract_repr.is_implicit contract with
-  | Some manager -> return (Some manager)
-  | None -> Storage.Contract.Delegate.get_option c contract
+  Storage.Contract.Delegate.get_option c contract
 
 let get_contract_delegate_at_cycle c cycle contract =
   match Contract_repr.is_implicit contract with
diff --git a/src/proto_alpha/lib_protocol/src/storage.ml b/src/proto_alpha/lib_protocol/src/storage.ml
index 8ac7d9049..ae5194b0b 100644
--- a/src/proto_alpha/lib_protocol/src/storage.ml
+++ b/src/proto_alpha/lib_protocol/src/storage.ml
@@ -65,9 +65,8 @@ module Contract = struct
       (Make_value(Bool))
 
   module Delegatable =
-    Indexed_context.Make_map
+    Indexed_context.Make_set
       (struct let name = ["delegatable"] end)
-      (Make_value(Bool))
 
   module Delegate =
     Make_indexed_data_snapshotable_storage
diff --git a/src/proto_alpha/lib_protocol/src/storage.mli b/src/proto_alpha/lib_protocol/src/storage.mli
index eb368d714..21bee92d4 100644
--- a/src/proto_alpha/lib_protocol/src/storage.mli
+++ b/src/proto_alpha/lib_protocol/src/storage.mli
@@ -114,9 +114,8 @@ module Contract : sig
      and type value = bool
      and type t := Raw_context.t
 
-  module Delegatable : Indexed_data_storage
-    with type key = Contract_repr.t
-     and type value = bool
+  module Delegatable : Data_set_storage
+    with type elt = Contract_repr.t
      and type t := Raw_context.t
 
   module Counter : Indexed_data_storage