diff --git a/lib/logging/core.ml b/lib/logging/core.ml
new file mode 100644
index 0000000..8f6482f
--- /dev/null
+++ b/lib/logging/core.ml
@@ -0,0 +1,19 @@
+type level =
+  | TRACE (* 0 *)
+  | DEBUG (* 1 *)
+  | INFO  (* 2 *)
+  | WARN  (* 3 *)
+  | ERROR (* 4 *)
+
+external int_of_level : level -> int = "%identity"
+
+type writer =
+  ts:Time.t ->
+  ns:string ->
+  lvl:level ->
+  string ->
+  unit
+
+let ( +++ ) w1 w2 ~ts ~ns ~lvl msg =
+  w1 ~ts ~ns ~lvl msg;
+  w2 ~ts ~ns ~lvl msg
diff --git a/lib/logging/logging.ml b/lib/logging/logging.ml
index 33e8294..0923e4d 100644
--- a/lib/logging/logging.ml
+++ b/lib/logging/logging.ml
@@ -1,32 +1,4 @@
-type level =
-  | TRACE (* 0 *)
-  | DEBUG (* 1 *)
-  | INFO  (* 2 *)
-  | WARN  (* 3 *)
-  | ERROR (* 4 *)
-
-external int_of_level : level -> int = "%identity"
-
-module Time = struct
-  (* TODO: abstract this? *)
-  type t = Ptime.t
-  let stamp = Ptime_clock.now
-  let pp = Ptime.pp_rfc3339 ()
-             ?tz_offset_s:(Ptime_clock.current_tz_offset_s ())
-  let to_string x =
-    Format.asprintf "%a" pp x
-end
-
-type writer =
-  ts:Time.t ->
-  ns:string ->
-  lvl:level ->
-  string ->
-  unit
-
-let ( +++ ) w1 w2 ~ts ~ns ~lvl msg =
-  w1 ~ts ~ns ~lvl msg;
-  w2 ~ts ~ns ~lvl msg
+include Core
 
 type logger = {
   namespace : string;
@@ -115,121 +87,6 @@ let rec add_writer_rec min_level writer parent_logger logger =
 let[@inline] add_writer ?(min_level = WARN) writer =
   add_writer_rec (int_of_level min_level) writer root_logger root_logger.child
 
-module Pretty = struct
-  type t = {
-    mutex : Mutex.t;
-    bp : Buffer.t;
-    mutable align_to : int;
-    out : out_channel;
-    flags : int;
-  }
-
-  type config = {
-    color : bool;
-    timestamp : bool;
-    namespace : bool;
-    level : bool;
-  }
-
-  let _fl_c = 1 (* color *)
-  let _fl_t = 2 (* timestamp *)
-  let _fl_n = 4 (* namespace *)
-  let _fl_l = 8 (* level *)
-  let _fl_ct = _fl_c + _fl_t
-  let _fl_cl = _fl_c + _fl_l
-
-  let header = function
-    | TRACE -> "TRACE"
-    | DEBUG -> "DEBUG"
-    | INFO  -> "INFO"
-    | WARN  -> "WARN"
-    | ERROR -> "ERROR"
-
-  let ansi_header = function
-    | TRACE -> "\x1b[34m"
-    | DEBUG -> "\x1b[36m"
-    | INFO  -> "\x1b[32m"
-    | WARN  -> "\x1b[33m"
-    | ERROR -> "\x1b[31m"
-
-  let ansi_dim  = "\x1b[2m"
-  let ansi_bold = "\x1b[1m"
-  let ansi_off  = "\x1b[0m"
-
-  let pr_timestamp bp ts =
-    Buffer.add_string bp (Time.to_string ts)
-
-  let pr_spaces bp n =
-    for _ = 1 to n do
-      Buffer.add_char bp ' '
-    done
-
-  let rec pr_lines_rec indent bp s i =
-    match String.index_from s i '\n' with
-    | exception Not_found ->
-      Buffer.add_substring bp s i (String.length s - i)
-    | k ->
-      Buffer.add_substring bp s i (k + 1 - i);
-      pr_spaces bp indent;
-      pr_lines_rec indent bp s (k + 1)
-
-  let pr_lines ~indent bp s =
-    pr_lines_rec indent bp s 0
-
-  let make (out : out_channel) (cfg : config) = {
-    mutex = Mutex.create ();
-    bp = Buffer.create 512;
-    align_to = 0;
-    out;
-    flags = (if cfg.color     then _fl_c else 0) +
-            (if cfg.timestamp then _fl_t else 0) +
-            (if cfg.namespace then _fl_n else 0) +
-            (if cfg.level     then _fl_l else 0)
-  }
-
-  let pr_msg bp msg ts ns lvl ~align ~indent ~f =
-    begin
-      if f _fl_ct then Buffer.add_string bp ansi_dim;
-      if f _fl_t  then Printf.bprintf bp "%a " pr_timestamp ts;
-      if f _fl_ct then Buffer.add_string bp ansi_off;
-
-      if f _fl_n then Printf.bprintf bp "%s " ns;
-      if f _fl_n then pr_spaces bp (align bp);
-
-      if f _fl_cl then Buffer.add_string bp (ansi_header lvl);
-      if f _fl_l then Printf.bprintf bp "%-5s " (header lvl);
-      if f _fl_cl then Buffer.add_string bp ansi_off;
-
-      if f _fl_c then Buffer.add_string bp ansi_bold;
-      pr_lines bp msg ~indent:(indent bp);
-      if f _fl_c then Buffer.add_string bp ansi_off;
-
-      Buffer.add_string bp "\n";
-    end
-
-  let writer t ~ts ~ns ~lvl msg =
-    let f mask = t.flags land mask = mask in
-    let align bp =
-      let n = t.align_to - Buffer.length bp in
-      t.align_to <- Buffer.length bp;
-      n
-    in
-    let indent bp =
-      Buffer.length bp
-      - (if f _fl_c  then 4 else 0)
-      - (if f _fl_ct then 8 else 0)
-      - (if f _fl_cl then 9 else 0)
-    in
-    begin
-      Mutex.lock t.mutex;
-      pr_msg t.bp msg ts ns lvl ~align ~indent ~f;
-      Buffer.output_buffer t.out t.bp;
-      flush t.out;
-      Buffer.clear t.bp;
-      Mutex.unlock t.mutex
-    end
-end
-
 let init_pretty_writer
       ?min_level
       ?(color = true)
diff --git a/lib/logging/pretty.ml b/lib/logging/pretty.ml
new file mode 100644
index 0000000..cab42eb
--- /dev/null
+++ b/lib/logging/pretty.ml
@@ -0,0 +1,115 @@
+open Core
+
+type t = {
+  mutex : Mutex.t;
+  bp : Buffer.t;
+  mutable align_to : int;
+  out : out_channel;
+  flags : int;
+}
+
+type config = {
+  color : bool;
+  timestamp : bool;
+  namespace : bool;
+  level : bool;
+}
+
+let _fl_c = 1 (* color *)
+let _fl_t = 2 (* timestamp *)
+let _fl_n = 4 (* namespace *)
+let _fl_l = 8 (* level *)
+let _fl_ct = _fl_c + _fl_t
+let _fl_cl = _fl_c + _fl_l
+
+let header = function
+  | TRACE -> "TRACE"
+  | DEBUG -> "DEBUG"
+  | INFO  -> "INFO"
+  | WARN  -> "WARN"
+  | ERROR -> "ERROR"
+
+let ansi_header = function
+  | TRACE -> "\x1b[34m"
+  | DEBUG -> "\x1b[36m"
+  | INFO  -> "\x1b[32m"
+  | WARN  -> "\x1b[33m"
+  | ERROR -> "\x1b[31m"
+
+let ansi_dim  = "\x1b[2m"
+let ansi_bold = "\x1b[1m"
+let ansi_off  = "\x1b[0m"
+
+let pr_timestamp bp ts =
+  Buffer.add_string bp (Time.to_string ts)
+
+let pr_spaces bp n =
+  for _ = 1 to n do
+    Buffer.add_char bp ' '
+  done
+
+let rec pr_lines_rec indent bp s i =
+  match String.index_from s i '\n' with
+  | exception Not_found ->
+    Buffer.add_substring bp s i (String.length s - i)
+  | k ->
+    Buffer.add_substring bp s i (k + 1 - i);
+    pr_spaces bp indent;
+    pr_lines_rec indent bp s (k + 1)
+
+let pr_lines ~indent bp s =
+  pr_lines_rec indent bp s 0
+
+let make (out : out_channel) (cfg : config) = {
+  mutex = Mutex.create ();
+  bp = Buffer.create 512;
+  align_to = 0;
+  out;
+  flags = (if cfg.color     then _fl_c else 0) +
+          (if cfg.timestamp then _fl_t else 0) +
+          (if cfg.namespace then _fl_n else 0) +
+          (if cfg.level     then _fl_l else 0)
+}
+
+let pr_msg bp msg ts ns lvl ~align ~indent ~f =
+  begin
+    if f _fl_ct then Buffer.add_string bp ansi_dim;
+    if f _fl_t  then Printf.bprintf bp "%a " pr_timestamp ts;
+    if f _fl_ct then Buffer.add_string bp ansi_off;
+
+    if f _fl_n then Printf.bprintf bp "%s " ns;
+    if f _fl_n then pr_spaces bp (align bp);
+
+    if f _fl_cl then Buffer.add_string bp (ansi_header lvl);
+    if f _fl_l then Printf.bprintf bp "%-5s " (header lvl);
+    if f _fl_cl then Buffer.add_string bp ansi_off;
+
+    if f _fl_c then Buffer.add_string bp ansi_bold;
+    pr_lines bp msg ~indent:(indent bp);
+    if f _fl_c then Buffer.add_string bp ansi_off;
+
+    Buffer.add_string bp "\n";
+  end
+
+let writer t ~ts ~ns ~lvl msg =
+  let f mask = t.flags land mask = mask in
+  let align bp =
+    let n = t.align_to - Buffer.length bp in
+    t.align_to <- Buffer.length bp;
+    n
+  in
+  let indent bp =
+    Buffer.length bp
+    - (if f _fl_c  then 4 else 0)
+    - (if f _fl_ct then 8 else 0)
+    - (if f _fl_cl then 9 else 0)
+  in
+  begin
+    Mutex.lock t.mutex;
+    pr_msg t.bp msg ts ns lvl ~align ~indent ~f;
+    Buffer.output_buffer t.out t.bp;
+    flush t.out;
+    Buffer.clear t.bp;
+    Mutex.unlock t.mutex
+  end
+
diff --git a/lib/logging/time.ml b/lib/logging/time.ml
new file mode 100644
index 0000000..00e0b46
--- /dev/null
+++ b/lib/logging/time.ml
@@ -0,0 +1,5 @@
+type t = Ptime.t
+let stamp = Ptime_clock.now
+let pp = Ptime.pp_rfc3339 ()
+           ?tz_offset_s:(Ptime_clock.current_tz_offset_s ())
+let to_string x = Format.asprintf "%a" pp x