diff --git a/src/node/net/p2p_connection.ml b/src/node/net/p2p_connection.ml
index 93da2e14e..35c521cdf 100644
--- a/src/node/net/p2p_connection.ml
+++ b/src/node/net/p2p_connection.ml
@@ -10,8 +10,6 @@
 (* TODO encode/encrypt before to push into the writer pipe. *)
 (* TODO patch Sodium.Box to avoid allocation of the encrypted buffer.*)
 (* TODO patch Data_encoding for continuation-based binary writer/reader. *)
-(* TODO use queue bound by memory size of its elements, not by the
-        number of elements. *)
 (* TODO test `close ~wait:true`. *)
 (* TODO nothing in welcoming message proves that the incoming peer is
         the owner of the public key... only the first message will
@@ -247,6 +245,11 @@ module Reader = struct
         Lwt.return_unit
 
   let run ?size conn encoding canceler =
+    let compute_size = function
+      | Ok (size, _) -> (Sys.word_size / 8) * 11 + size
+      | Error _ -> 0 (* we push Error only when we close the socket,
+                        we don't fear memory leaks in that case... *) in
+    let size = map_option size ~f:(fun max -> (max, compute_size)) in
     let st =
       { canceler ; conn ; encoding ;
         messages = Lwt_pipe.create ?size () ;
@@ -303,6 +306,13 @@ module Writer = struct
         Lwt.return_unit
 
   let run ?size conn encoding canceler =
+    let compute_size = function
+      | msg, None ->
+          10 * (Sys.word_size / 8) + Data_encoding.Binary.length encoding msg
+      | msg, Some _ ->
+          18 * (Sys.word_size / 8) + Data_encoding.Binary.length encoding msg
+    in
+    let size = map_option size ~f:(fun max -> max, compute_size) in
     let st =
       { canceler ; conn ; encoding ;
         messages = Lwt_pipe.create ?size () ;
@@ -350,24 +360,9 @@ let accept
   let canceler = Canceler.create () in
   let conn = { fd ; info ; cryptobox_data } in
   let reader =
-    let compute_size = function
-      | Ok (size, _) -> (Sys.word_size / 8) * 11 + size
-      | Error err -> (Sys.word_size / 8) * (3 + 3 * (List.length err))
-    in
-    let size = map_option incoming_message_queue_size
-        ~f:(fun qs -> (qs, compute_size)) in
-    Reader.run ?size conn encoding canceler
+    Reader.run ?size:incoming_message_queue_size conn encoding canceler
   and writer =
-    let compute_size = function
-      | msg, None ->
-          10 * (Sys.word_size / 8) + Data_encoding.Binary.length encoding msg
-      | msg, Some _ ->
-          18 * (Sys.word_size / 8) + Data_encoding.Binary.length encoding msg
-    in
-    let size = map_option outgoing_message_queue_size
-        ~f:(fun qs -> qs, compute_size)
-    in
-    Writer.run ?size conn encoding canceler in
+    Writer.run ?size:outgoing_message_queue_size conn encoding canceler in
   let conn = { conn ; reader ; writer } in
   Canceler.on_cancel canceler begin fun () ->
     P2p_io_scheduler.close fd >>= fun _ ->
diff --git a/src/node/net/p2p_connection_pool.ml b/src/node/net/p2p_connection_pool.ml
index 55e4b8205..4d9a34161 100644
--- a/src/node/net/p2p_connection_pool.ml
+++ b/src/node/net/p2p_connection_pool.ml
@@ -248,12 +248,13 @@ let active_connections pool = Gid.Table.length pool.connected_gids
 let create_connection pool conn id_point pi gi =
   let gid = Gid_info.gid gi in
   let canceler = Canceler.create () in
-  let size = map_option pool.config.incoming_app_message_queue_size
-      ~f:(fun qs -> qs, fun (size, _) -> (Sys.word_size / 8) * (11 + size))
-  in
+  let size =
+    map_option pool.config.incoming_app_message_queue_size
+      ~f:(fun qs -> qs, fun (size, _) -> (Sys.word_size / 8) * 11 + size) in
   let messages = Lwt_pipe.create ?size () in
   let callback =
-    { Answerer.message = (fun size msg -> Lwt_pipe.push messages (size, msg)) ;
+    { Answerer.message =
+        (fun size msg -> Lwt_pipe.push messages (size, msg)) ;
       advertise = register_new_points pool gid ;
       bootstrap = list_known_points pool gid ;
     } in
diff --git a/src/node/net/p2p_io_scheduler.ml b/src/node/net/p2p_io_scheduler.ml
index 8ffe2e3cf..af74ac9b9 100644
--- a/src/node/net/p2p_io_scheduler.ml
+++ b/src/node/net/p2p_io_scheduler.ml
@@ -315,11 +315,12 @@ let create
 
 exception Closed
 
-let read_size_fun = function
+let read_size = function
   | Ok buf -> (Sys.word_size / 8) * 8 + MBytes.length buf
-  | Error exns -> (Sys.word_size / 8) * (1 + 3 * (List.length exns))
+  | Error _ -> 0 (* we push Error only when we close the socket,
+                    we don't fear memory leaks in that case... *)
 
-let write_size_fun mbytes = (Sys.word_size / 8) * 6 + MBytes.length mbytes
+let write_size mbytes = (Sys.word_size / 8) * 6 + MBytes.length mbytes
 
 let register =
   let cpt = ref 0 in
@@ -330,10 +331,12 @@ let register =
   end else begin
     let id = incr cpt; !cpt in
     let canceler = Canceler.create () in
-    let read_size_arg = map_option st.read_queue_size ~f:(fun v -> v, read_size_fun) in
-    let write_size_arg = map_option st.write_queue_size ~f:(fun v -> v, write_size_fun) in
-    let read_queue = Lwt_pipe.create ?size:read_size_arg () in
-    let write_queue = Lwt_pipe.create ?size:write_size_arg () in
+    let read_size =
+      map_option st.read_queue_size ~f:(fun v -> v, read_size) in
+    let write_size =
+      map_option st.write_queue_size ~f:(fun v -> v, write_size) in
+    let read_queue = Lwt_pipe.create ?size:read_size () in
+    let write_queue = Lwt_pipe.create ?size:write_size () in
     let read_conn =
       ReadScheduler.create_connection
         st.read_scheduler (conn, st.read_buffer_size) read_queue canceler id
diff --git a/src/utils/lwt_pipe.ml b/src/utils/lwt_pipe.ml
index 4051bcce8..0fede0225 100644
--- a/src/utils/lwt_pipe.ml
+++ b/src/utils/lwt_pipe.ml
@@ -21,7 +21,8 @@ type 'a t =
   }
 
 let create ?size () =
-  let max_size, compute_size = match size with
+  let max_size, compute_size =
+    match size with
     | None -> max_int, (fun _ -> 0)
     | Some (max_size, compute_size) ->
         max_size, (fun e -> 4 * (Sys.word_size / 8) + compute_size e) in
@@ -77,16 +78,15 @@ exception Closed
 
 let rec push ({ closed ; queue ; current_size ;
                 max_size ; compute_size} as q) elt =
-  if closed then Lwt.fail Closed
-  else
-    let elt_size = compute_size elt in
-  if current_size + elt_size < max_size then begin
+  let elt_size = compute_size elt in
+  if closed then
+    Lwt.fail Closed
+  else if current_size + elt_size < max_size || Queue.is_empty queue then begin
     Queue.push (elt_size, elt) queue ;
     q.current_size <- current_size + elt_size ;
     notify_push q ;
     Lwt.return_unit
-  end
-  else
+  end else
     wait_pop q >>= fun () ->
     push q elt
 
@@ -95,7 +95,7 @@ let rec push_now ({ closed ; queue ; compute_size ;
                   } as q) elt =
   if closed then raise Closed ;
   let elt_size = compute_size elt in
-  (current_size + elt_size < max_size)
+  (current_size + elt_size < max_size || Queue.is_empty queue)
   && begin
     Queue.push (elt_size, elt) queue ;
     q.current_size <- current_size + elt_size ;
diff --git a/test/test_p2p_io_scheduler.ml b/test/test_p2p_io_scheduler.ml
index 81efc7822..5a5b7937f 100644
--- a/test/test_p2p_io_scheduler.ml
+++ b/test/test_p2p_io_scheduler.ml
@@ -170,8 +170,8 @@ let max_download_speed = ref None
 let max_upload_speed = ref None
 
 let read_buffer_size = ref (1 lsl 14)
-let read_queue_size = ref (Some (4096 * 16))
-let write_queue_size = ref (Some (4096 * 16))
+let read_queue_size = ref (Some (1 lsl 14))
+let write_queue_size = ref (Some (1 lsl 14))
 
 let delay = ref 60.
 let clients = ref 8