diff --git a/src/proto_alpha/lib_baking/client_baking_forge.ml b/src/proto_alpha/lib_baking/client_baking_forge.ml
index 3fc8efc0b..d302f0955 100644
--- a/src/proto_alpha/lib_baking/client_baking_forge.ml
+++ b/src/proto_alpha/lib_baking/client_baking_forge.ml
@@ -29,9 +29,7 @@ let forge_block_header
     let proof_of_work_nonce = generate_proof_of_work_nonce () in
     let protocol_data : Block_header.protocol_data =
       { priority ; seed_nonce_hash ; proof_of_work_nonce } in
-    let faked_header : Block_header.t =
-      { shell ; protocol_data ; signature = Signature.zero } in
-    if Baking.check_header_hash faked_header stamp_threshold then
+    if Baking.check_header_proof_of_work_stamp shell protocol_data stamp_threshold then
       let unsigned_header =
         Alpha_context.Block_header.forge_unsigned shell protocol_data in
       Client_keys.append cctxt delegate_sk unsigned_header >>=? fun signed_header ->
diff --git a/src/proto_alpha/lib_protocol/src/baking.ml b/src/proto_alpha/lib_protocol/src/baking.ml
index f38b09570..1c2e96322 100644
--- a/src/proto_alpha/lib_protocol/src/baking.ml
+++ b/src/proto_alpha/lib_protocol/src/baking.ml
@@ -251,19 +251,18 @@ let check_hash hash stamp_threshold =
   let word = MBytes.get_int64 bytes 0 in
   Compare.Uint64.(word <= stamp_threshold)
 
-let check_header_hash header stamp_threshold =
+let check_header_proof_of_work_stamp shell protocol_data stamp_threshold =
   let hash =
-    Block_header.hash_raw
-      { shell = header.Block_header.shell ;
-        protocol_data =
-          Data_encoding.Binary.to_bytes
-            Block_header.protocol_data_encoding
-            header.protocol_data } in
+    Block_header.hash
+      { shell ; protocol_data ; signature = Signature.zero } in
   check_hash hash stamp_threshold
 
 let check_proof_of_work_stamp ctxt block =
   let proof_of_work_threshold = Constants.proof_of_work_threshold ctxt in
-  if check_header_hash block proof_of_work_threshold then
+  if check_header_proof_of_work_stamp
+      block.Block_header.shell
+      block.protocol_data
+      proof_of_work_threshold then
     return ()
   else
     fail Invalid_stamp
diff --git a/src/proto_alpha/lib_protocol/src/baking.mli b/src/proto_alpha/lib_protocol/src/baking.mli
index c2162e398..2b41d71a9 100644
--- a/src/proto_alpha/lib_protocol/src/baking.mli
+++ b/src/proto_alpha/lib_protocol/src/baking.mli
@@ -103,7 +103,12 @@ val first_endorsement_slots:
     the given key *)
 val check_signature: Block_header.t -> public_key -> unit tzresult Lwt.t
 
-val check_header_hash: Block_header.t -> int64 -> bool
+(** Checks if the header that would be built from the given components
+    is valid for the given diffculty. The signature is not passed as it
+    is does not impact the proof-of-work stamp. The stamp is checked on
+    the hash of a block header whose signature has been zeroed-out. *)
+val check_header_proof_of_work_stamp:
+  Block_header.shell_header -> Block_header.protocol_data -> int64 -> bool
 
 (** verify if the proof of work stamp is valid *)
 val check_proof_of_work_stamp: