diff --git a/ocaml/Qpackage.ml b/ocaml/Qpackage.ml
index bd0d34fc..8011b23b 100644
--- a/ocaml/Qpackage.ml
+++ b/ocaml/Qpackage.ml
@@ -127,3 +127,14 @@ let get_ezfio_default directory data =
   |> aux 
 ;;
 
+let ezfio_work ezfio_file = 
+  let result = 
+    Filename.concat ezfio_file  "work"
+  in
+  begin
+    match Sys.is_directory result with
+    | `Yes -> ()
+    | _ -> Unix.mkdir result
+  end;
+  result
+;;
diff --git a/ocaml/TaskServer.ml b/ocaml/TaskServer.ml
index 6f012981..cfc22cfc 100644
--- a/ocaml/TaskServer.ml
+++ b/ocaml/TaskServer.ml
@@ -48,20 +48,21 @@ let zmq_context =
   ZMQ.Context.create ()
 
 
-let bind_socket ~socket_type ~socket ~address =
+let bind_socket ~socket_type ~socket ~port =
   let rec loop = function
   | 0 -> failwith @@ Printf.sprintf
-        "Unable to bind the %s socket : %s "
-        socket_type address
+        "Unable to bind the %s socket to port : %d "
+        socket_type port
   | -1 -> ()
   | i -> 
       try
-        ZMQ.Socket.bind socket address;
+        ZMQ.Socket.bind socket @@ Printf.sprintf "tcp://*:%d" port;
         loop (-1)
       with
       | Unix.Unix_error _ -> (Time.pause @@ Time.Span.of_float 1. ; loop (i-1) )
       | other_exception -> raise other_exception
-  in loop 60
+  in loop 60;
+  ZMQ.Socket.bind socket @@ Printf.sprintf "ipc:///tmp/qp_run:%d" port
 
 
 let hostname = lazy (
@@ -115,7 +116,7 @@ let stop ~port =
     let req_socket =
       ZMQ.Socket.create zmq_context ZMQ.Socket.req
     and address =
-      Printf.sprintf "tcp://%s:%d" (Lazy.force ip_address) port
+      Printf.sprintf "ipc:///tmp/qp_run:%d" port
     in
     ZMQ.Socket.set_linger_period req_socket 1_000_000;
     ZMQ.Socket.connect req_socket address;
@@ -567,10 +568,8 @@ let start_pub_thread ~port =
 
       let pub_socket =
         ZMQ.Socket.create zmq_context ZMQ.Socket.pub
-      and address =
-        Printf.sprintf "tcp://*:%d" port
       in
-      bind_socket ~socket_type:"PUB" ~socket:pub_socket ~address;
+      bind_socket ~socket_type:"PUB" ~socket:pub_socket ~port;
 
       let pollitem =
         ZMQ.Poll.mask_of 
@@ -608,7 +607,7 @@ let run ~port =
     and address = 
       "inproc://pair" 
     in
-    bind_socket "PAIR" pair_socket address;
+    ZMQ.Socket.bind pair_socket address;
 
     let pub_thread = 
       start_pub_thread ~port:(port+1) ()
@@ -617,11 +616,9 @@ let run ~port =
     (** Bind REP socket *)
     let rep_socket =
       ZMQ.Socket.create zmq_context ZMQ.Socket.rep
-    and address =
-      Printf.sprintf "tcp://*:%d" port
     in
     ZMQ.Socket.set_linger_period rep_socket 1_000_000;
-    bind_socket "REP" rep_socket address;
+    bind_socket "REP" rep_socket port;
 
     let initial_program_state =
     {   queue = Queuing_system.create () ;
@@ -721,6 +718,7 @@ let run ~port =
 
     ZMQ.Socket.send pair_socket @@ string_of_pub_state Stopped;
     Thread.join pub_thread;
+    ZMQ.Socket.close rep_socket
 
 
 
diff --git a/ocaml/TaskServer.mli b/ocaml/TaskServer.mli
index f923a18a..e1baab12 100644
--- a/ocaml/TaskServer.mli
+++ b/ocaml/TaskServer.mli
@@ -23,9 +23,9 @@ val debug : string -> unit
 (** ZeroMQ context *)
 val zmq_context : ZMQ.Context.t
 
-(** Bind a ZMQ socket *)
+(** Bind a ZMQ socket to a TCP port and to an IPC file /tmp/qp_run.<port> *)
 val bind_socket :
-  socket_type:string -> socket:'a ZMQ.Socket.t -> address:string -> unit
+  socket_type:string -> socket:'a ZMQ.Socket.t -> port:int -> unit
 
 (** Name of the host on which the server runs *)
 val hostname : string lazy_t
diff --git a/ocaml/qp_run.ml b/ocaml/qp_run.ml
index 8a221614..e8c8d05a 100644
--- a/ocaml/qp_run.ml
+++ b/ocaml/qp_run.ml
@@ -15,7 +15,7 @@ let print_list () =
 let () = 
   Random.self_init ()
 
-let run ~master exe ezfio_file =
+let run slave exe ezfio_file =
 
 
   (** Check availability of the ports *)
@@ -28,7 +28,7 @@ let run ~master exe ezfio_file =
     in
     let rec try_new_port port_number =
       try 
-        List.iter [ 0;1;2;3;4 ] ~f:(fun i ->
+        List.iter [ 0;1;2;3;4;5;6;7;8;9 ] ~f:(fun i ->
             let address = 
               Printf.sprintf "tcp://%s:%d" (Lazy.force TaskServer.ip_address) (port_number+i)
             in
@@ -75,16 +75,23 @@ let run ~master exe ezfio_file =
     | 0 -> ()
     | i -> failwith "Error: Input inconsistent\n"
   end;
-  begin
-    match master with
-    | Some address -> Unix.putenv ~key:"QP_RUN_ADDRESS_MASTER" ~data:address
-    | None -> ()
-  end;
 
-  (** Start task server *)
-  let address =
-    Printf.sprintf "tcp://%s:%d" (Lazy.force TaskServer.ip_address) port_number
+  let qp_run_address_filename = 
+   Filename.concat (Qpackage.ezfio_work ezfio_file) "qp_run_address"
   in
+
+  let () = 
+    if slave then
+      try
+        let address = 
+          In_channel.read_all qp_run_address_filename
+          |> String.strip
+        in
+        Unix.putenv ~key:"QP_RUN_ADDRESS_MASTER" ~data:address
+      with Sys_error _ -> failwith "No master is not running"
+  in
+       
+  (** Start task server *)
   let task_thread =
      let thread = 
       Thread.create ( fun () -> 
@@ -92,7 +99,16 @@ let run ~master exe ezfio_file =
      in
      thread ();
   in
+  let address =
+    Printf.sprintf "tcp://%s:%d" (Lazy.force TaskServer.ip_address) port_number
+  in
   Unix.putenv ~key:"QP_RUN_ADDRESS" ~data:address;
+  let () = 
+    if (not slave) then
+      Out_channel.with_file qp_run_address_filename  ~f:(
+        fun oc -> Out_channel.output_lines oc [address]) 
+  in
+
 
   (** Run executable *)
   let prefix = 
@@ -111,6 +127,8 @@ let run ~master exe ezfio_file =
 
   TaskServer.stop ~port:port_number;
   Thread.join task_thread;
+  if (not slave) then
+    Sys.remove qp_run_address_filename;
 
   let duration = Time.diff (Time.now()) time_start 
   |> Core.Span.to_string in
@@ -119,8 +137,8 @@ let run ~master exe ezfio_file =
 let spec = 
   let open Command.Spec in
   empty
-  +> flag "master" (optional string)
-     ~doc:("address Address of the master process")
+  +> flag "slave" no_arg
+     ~doc:(" Needed for slave tasks")
   +> anon ("executable" %: string)
   +> anon ("ezfio_file" %: string)
 ;;
@@ -138,8 +156,8 @@ Executes a Quantum Package binary file among these:\n\n"
     )
   )
   spec
-  (fun master exe ezfio_file () ->
-    run ~master exe ezfio_file
+  (fun slave exe ezfio_file () ->
+    run slave exe ezfio_file
   )
   |> Command.run   ~version: Git.sha1   ~build_info: Git.message
 
diff --git a/src/ZMQ/utils.irp.f b/src/ZMQ/utils.irp.f
index c3a55a05..61fb45de 100644
--- a/src/ZMQ/utils.irp.f
+++ b/src/ZMQ/utils.irp.f
@@ -670,12 +670,16 @@ subroutine disconnect_from_taskserver(zmq_to_qp_run_socket, &
   message = trim(message(1:rc))
   
   read(message,*) reply, state
-  if ( (trim(reply) /= 'disconnect_reply').or.                       &
-        (trim(state) /= zmq_state) ) then
-    print *,  'Unable to disconnect : ', zmq_state
-    print *,  trim(message)
-    stop -1
+  if ((trim(reply) == 'disconnect_reply').and.(trim(state) == trim(zmq_state))) then
+    return
   endif
+  if (trim(message) == 'error No job is running') then
+    return
+  endif
+
+  print *,  'Unable to disconnect : ', trim(zmq_state)
+  print *,  trim(message)
+  stop -1
 
 end