diff --git a/src/proto_alpha/lib_protocol/src/constants_repr.ml b/src/proto_alpha/lib_protocol/src/constants_repr.ml
index 53d7dfd24..bd21d1acd 100644
--- a/src/proto_alpha/lib_protocol/src/constants_repr.ml
+++ b/src/proto_alpha/lib_protocol/src/constants_repr.ml
@@ -221,5 +221,3 @@ let encoding =
     (fun { fixed ; parametric } -> (fixed, parametric))
     (fun (fixed , parametric) -> { fixed ; parametric })
     (merge_objs fixed_encoding parametric_encoding)
-
-type error += Constant_read of exn
diff --git a/src/proto_alpha/lib_protocol/src/helpers_services.ml b/src/proto_alpha/lib_protocol/src/helpers_services.ml
index 7fea3a553..7f2362567 100644
--- a/src/proto_alpha/lib_protocol/src/helpers_services.ml
+++ b/src/proto_alpha/lib_protocol/src/helpers_services.ml
@@ -9,9 +9,7 @@
 
 open Alpha_context
 
-type error +=
-  | Cannot_parse_operation (* `Branch *)
-  | Cant_parse_block_header
+type error += Cannot_parse_operation (* `Branch *)
 
 let () =
   register_error_kind
diff --git a/src/proto_alpha/lib_protocol/src/helpers_services.mli b/src/proto_alpha/lib_protocol/src/helpers_services.mli
index e46e11c1d..6d58c5c74 100644
--- a/src/proto_alpha/lib_protocol/src/helpers_services.mli
+++ b/src/proto_alpha/lib_protocol/src/helpers_services.mli
@@ -9,9 +9,7 @@
 
 open Alpha_context
 
-type error +=
-  | Cannot_parse_operation (* `Branch *)
-  | Cant_parse_block_header
+type error += Cannot_parse_operation (* `Branch *)
 
 val current_level:
   'a #RPC_context.simple ->