diff --git a/src/subscriber/dune b/src/subscriber/dune
deleted file mode 100644
index b8b3da0..0000000
--- a/src/subscriber/dune
+++ /dev/null
@@ -1,18 +0,0 @@
-(library
- (name trace_subscriber)
- (public_name trace.subscriber)
- (private_modules time_ thread_)
- (libraries
-  (re_export trace.core)
-  (select
-   thread_.ml
-   from
-   (threads -> thread_.real.ml)
-   (-> thread_.dummy.ml))
-  (select
-   time_.ml
-   from
-   (mtime mtime.clock.os -> time_.mtime.ml)
-   (mtime mtime.clock.jsoo -> time_.mtime.ml)
-   (unix -> time_.unix.ml)
-   (-> time_.dummy.ml))))
diff --git a/src/subscriber/span_sub.ml b/src/subscriber/span_sub.ml
deleted file mode 100644
index 3be5ef9..0000000
--- a/src/subscriber/span_sub.ml
+++ /dev/null
@@ -1,39 +0,0 @@
-(** Subscriber span.
-
-    This is the concrete representation of spans used in [Trace_subscriber].
-
-    @since NEXT_RELEASE *)
-
-open Trace_core
-
-type span_id = int64
-(** Unique ID *)
-
-type trace_id = int64
-(** Unique trace ID *)
-
-let dummy_span_id = Int64.min_int
-
-type span_flavor =
-  [ `Sync
-  | `Async
-  ]
-
-type t = {
-  id: span_id;
-  name: string;
-  __FUNCTION__: string option;
-  __FILE__: string;
-  __LINE__: int;
-  time_ns: int64;  (** Time the span was entered. *)
-  mutable time_exit_ns: int64;
-      (** Time the span was exited. Set at exit, [Int64.max_int] otherwise *)
-  trace_id: trace_id;
-  tid: int;  (** Thread in which span was created *)
-  parent: parent;
-  flavor: span_flavor;
-  params: extension_parameter list;
-  mutable data: (string * Trace_core.user_data) list;
-      (** Modified by [add_data_to_span] *)
-}
-(** The type of spans used by all subscribers. *)
diff --git a/src/subscriber/thread_.dummy.ml b/src/subscriber/thread_.dummy.ml
deleted file mode 100644
index 29ea74d..0000000
--- a/src/subscriber/thread_.dummy.ml
+++ /dev/null
@@ -1 +0,0 @@
-let[@inline] get_tid () = 0
diff --git a/src/subscriber/thread_.mli b/src/subscriber/thread_.mli
deleted file mode 100644
index 08e8ea1..0000000
--- a/src/subscriber/thread_.mli
+++ /dev/null
@@ -1,2 +0,0 @@
-val get_tid : unit -> int
-(** Get current thread ID *)
diff --git a/src/subscriber/thread_.real.ml b/src/subscriber/thread_.real.ml
deleted file mode 100644
index 51a172c..0000000
--- a/src/subscriber/thread_.real.ml
+++ /dev/null
@@ -1 +0,0 @@
-let[@inline] get_tid () = Thread.id @@ Thread.self ()
diff --git a/src/subscriber/time_.mtime.ml b/src/subscriber/time_.mtime.ml
deleted file mode 100644
index baa3f86..0000000
--- a/src/subscriber/time_.mtime.ml
+++ /dev/null
@@ -1,3 +0,0 @@
-let[@inline] get_time_ns () : int64 =
-  let t = Mtime_clock.now () in
-  Mtime.to_uint64_ns t
diff --git a/src/subscriber/time_.unix.ml b/src/subscriber/time_.unix.ml
deleted file mode 100644
index f7411c1..0000000
--- a/src/subscriber/time_.unix.ml
+++ /dev/null
@@ -1,3 +0,0 @@
-let[@inline] get_time_ns () : int64 =
-  let t = Unix.gettimeofday () in
-  Int64.of_float (t *. 1e9)
diff --git a/src/subscriber/trace_subscriber.ml b/src/subscriber/trace_subscriber.ml
index 35b864b..e6113bc 100644
--- a/src/subscriber/trace_subscriber.ml
+++ b/src/subscriber/trace_subscriber.ml
@@ -1,9 +1,6 @@
 open Trace_core
-module Callbacks = Callbacks
-module Subscriber = Subscriber
-module Span_sub = Span_sub
 
-type t = Subscriber.t
+type t = Collector.t
 
 module Private_ = struct
   let mock = ref false
@@ -131,17 +128,3 @@ end
 (** A collector that calls the callbacks of subscriber *)
 let collector (self : Subscriber.t) : collector =
   Collector.C_some (self, coll_cbs)
-
-module Span_id_generator = struct
-  type t = int A.t
-
-  let create () = A.make 0
-  let[@inline] gen self = A.fetch_and_add self 1 |> Int64.of_int
-end
-
-module Trace_id_generator = struct
-  type t = int A.t
-
-  let create () = A.make 0
-  let[@inline] gen self = A.fetch_and_add self 1 |> Int64.of_int
-end