diff --git a/CHANGES.md b/CHANGES.md
index 5ecfb73..d6a8756 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,7 @@
+# unreleased
+
+- Added `copy`
+
 # v0.2.0 2021-02-10
 
 - Added `to_bytes` and `of_bytes`.
diff --git a/src/bloomf.ml b/src/bloomf.ml
index 7f5fb3f..df290a0 100644
--- a/src/bloomf.ml
+++ b/src/bloomf.ml
@@ -1,6 +1,7 @@
 type priv = { m : int; k : int; p_len : (int * int) list; b : Bitv.t }
 type 'a t = priv
 
+let copy t = { m = t.m; k = t.k; p_len = t.p_len; b = Bitv.copy t.b }
 let rec gcd a b = if b = 0 then a else gcd b (a mod b)
 
 let partition_lengths m k =
@@ -142,6 +143,7 @@ module Make (H : Hashable) = struct
   type t = priv
 
   let create = create
+  let copy = copy
   let add bf data = add_priv bf (H.hash data)
   let mem bf data = mem_priv bf (H.hash data)
   let clear = clear
diff --git a/src/bloomf.mli b/src/bloomf.mli
index 95960c5..f91633e 100644
--- a/src/bloomf.mli
+++ b/src/bloomf.mli
@@ -22,6 +22,10 @@ val create : ?error_rate:float -> int -> 'a t
     @raise Invalid_argument
       if [error_rate] is not in \]0, 1\[, or [size] is negative. *)
 
+val copy : 'a t -> 'a t
+(** [copy t] copies the BF. The fresh returned BF is completely separated from
+    the given one. *)
+
 val add : 'a t -> 'a -> unit
 (** [add t e] adds [e] to [t]. *)
 
@@ -79,6 +83,7 @@ module Make (H : Hashable) : sig
   type t
 
   val create : ?error_rate:float -> int -> t
+  val copy : t -> t
   val add : t -> H.t -> unit
   val mem : t -> H.t -> bool
   val clear : t -> unit