diff --git a/src/proto_alpha/lib_protocol/bitset.ml b/src/proto_alpha/lib_protocol/bitset.ml
index a49c4264ac05e2f7c6f24d5e95ebef680f7cd140..7f7792bf0803b3a400a1b6ea6c7242b42f944890 100644
--- a/src/proto_alpha/lib_protocol/bitset.ml
+++ b/src/proto_alpha/lib_protocol/bitset.ml
@@ -39,6 +39,10 @@ let add field pos =
   error_when Compare.Int.(pos < 0) (Invalid_position pos) >>? fun () ->
   ok @@ Z.logor field Z.(shift_left one pos)
 
+let from_list positions = List.fold_left_e add empty positions
+
+let inter = Z.logand
+
 let () =
   let open Data_encoding in
   register_error_kind
diff --git a/src/proto_alpha/lib_protocol/bitset.mli b/src/proto_alpha/lib_protocol/bitset.mli
index c7bf12064147e29f5bfa456ddae1cad1616c3910..96b101a56cfcf1cdcf6b20b465d61d0c8fad9188 100644
--- a/src/proto_alpha/lib_protocol/bitset.mli
+++ b/src/proto_alpha/lib_protocol/bitset.mli
@@ -44,6 +44,13 @@ val mem : t -> int -> bool tzresult
     This functions returns [Invalid_input i] if [i] is negative. *)
 val add : t -> int -> t tzresult
 
+(** [from_list positions] folds [add] over the [positions] starting from [empty]. *)
+val from_list : int list -> t tzresult
+
+(** [inter field_l field_r] returns [field] which is result of the
+   logical "and" bit-wise from [field_l] and [field_r]. *)
+val inter : t -> t -> t
+
 (** [occupied_size_in_bits bitset] returns the current number of bits
    occupied by the [bitset]. *)
 val occupied_size_in_bits : t -> int