diff --git a/src/core/nanoev.ml b/src/core/nanoev.ml
index f0ea5c7..c15935e 100644
--- a/src/core/nanoev.ml
+++ b/src/core/nanoev.ml
@@ -1,13 +1,28 @@
 module Trace_ = Trace_
 
+exception Closed
+
 module Impl = struct
   type 'st ops = {
     clear: 'st -> unit;
     wakeup_from_outside: 'st -> unit;
+    close: 'st -> Unix.file_descr -> unit;
     on_readable:
-      'a 'b. 'st -> Unix.file_descr -> 'a -> 'b -> ('a -> 'b -> unit) -> unit;
+      'a 'b.
+      'st ->
+      Unix.file_descr ->
+      'a ->
+      'b ->
+      (closed:bool -> 'a -> 'b -> unit) ->
+      unit;
     on_writable:
-      'a 'b. 'st -> Unix.file_descr -> 'a -> 'b -> ('a -> 'b -> unit) -> unit;
+      'a 'b.
+      'st ->
+      Unix.file_descr ->
+      'a ->
+      'b ->
+      (closed:bool -> 'a -> 'b -> unit) ->
+      unit;
     run_after_s: 'a 'b. 'st -> float -> 'a -> 'b -> ('a -> 'b -> unit) -> unit;
     step: 'st -> unit;
   }
@@ -23,6 +38,7 @@ type t = Impl.t
 
 let[@inline] clear (Ev (ops, st)) = ops.clear st
 let[@inline] wakeup_from_outside (Ev (ops, st)) = ops.wakeup_from_outside st
+let[@inline] close (Ev (ops, st)) fd = ops.close st fd
 
 let[@inline] on_readable (Ev (ops, st)) fd x y f : unit =
   ops.on_readable st fd x y f
@@ -34,11 +50,3 @@ let[@inline] run_after_s (Ev (ops, st)) time x y f : unit =
   ops.run_after_s st time x y f
 
 let[@inline] step (Ev (ops, st)) : unit = ops.step st
-
-(*
-let rec read (self:t) fd buf i len : int =
-  match Unix.read fd buf i len with
-    | n -> n
-  | exception Unix.Unix_error (Unix, _, _) ->
-    read self fd buf i len
-*)
diff --git a/src/core/nanoev.mli b/src/core/nanoev.mli
index 2224efa..4792cd6 100644
--- a/src/core/nanoev.mli
+++ b/src/core/nanoev.mli
@@ -2,14 +2,29 @@
 
 type t
 
+exception Closed
+
 module Impl : sig
   type 'st ops = {
     clear: 'st -> unit;
     wakeup_from_outside: 'st -> unit;
+    close: 'st -> Unix.file_descr -> unit;
     on_readable:
-      'a 'b. 'st -> Unix.file_descr -> 'a -> 'b -> ('a -> 'b -> unit) -> unit;
+      'a 'b.
+      'st ->
+      Unix.file_descr ->
+      'a ->
+      'b ->
+      (closed:bool -> 'a -> 'b -> unit) ->
+      unit;
     on_writable:
-      'a 'b. 'st -> Unix.file_descr -> 'a -> 'b -> ('a -> 'b -> unit) -> unit;
+      'a 'b.
+      'st ->
+      Unix.file_descr ->
+      'a ->
+      'b ->
+      (closed:bool -> 'a -> 'b -> unit) ->
+      unit;
     run_after_s: 'a 'b. 'st -> float -> 'a -> 'b -> ('a -> 'b -> unit) -> unit;
     step: 'st -> unit;
   }
@@ -25,8 +40,15 @@ val wakeup_from_outside : t -> unit
 val step : t -> unit
 (** Run one step of the event loop until something happens *)
 
-val on_readable : t -> Unix.file_descr -> 'a -> 'b -> ('a -> 'b -> unit) -> unit
-val on_writable : t -> Unix.file_descr -> 'a -> 'b -> ('a -> 'b -> unit) -> unit
+val close : t -> Unix.file_descr -> unit
+(** Close the file descriptor and clean it up *)
+
+val on_readable :
+  t -> Unix.file_descr -> 'a -> 'b -> (closed:bool -> 'a -> 'b -> unit) -> unit
+
+val on_writable :
+  t -> Unix.file_descr -> 'a -> 'b -> (closed:bool -> 'a -> 'b -> unit) -> unit
+
 val run_after_s : t -> float -> 'a -> 'b -> ('a -> 'b -> unit) -> unit
 
 (**/**)
diff --git a/src/picos/nanoev_picos.ml b/src/picos/nanoev_picos.ml
index 45f5cc6..9920345 100644
--- a/src/picos/nanoev_picos.ml
+++ b/src/picos/nanoev_picos.ml
@@ -4,6 +4,8 @@ open struct
   let ( let@ ) = ( @@ )
 end
 
+exception Closed = Nanoev.Closed
+
 module Global_ = struct
   type st =
     | None
@@ -76,9 +78,12 @@ let retry_read_ fd f =
         Unix.Unix_error ((Unix.EAGAIN | Unix.EWOULDBLOCK | Unix.EINTR), _, _) ->
       Trace_.message "read must wait";
       let trigger = Picos.Trigger.create () in
-      Nanoev.on_readable ev fd trigger () (fun trigger () ->
+      let closed_r = ref false in
+      Nanoev.on_readable ev fd trigger closed_r (fun ~closed trigger closed_r ->
+          closed_r := closed;
           Picos.Trigger.signal trigger);
       Picos.Trigger.await trigger |> unwrap_;
+      if !closed_r then raise Closed;
       loop ()
   in
   loop ()
@@ -92,27 +97,42 @@ let retry_write_ fd f =
         Unix.Unix_error ((Unix.EAGAIN | Unix.EWOULDBLOCK | Unix.EINTR), _, _) ->
       Trace_.message "write must wait";
       let trigger = Picos.Trigger.create () in
-      Nanoev.on_writable ev fd trigger () (fun trigger () ->
+      let closed_r = ref false in
+      Nanoev.on_writable ev fd trigger closed_r (fun ~closed trigger closed_r ->
+          closed_r := closed;
           Picos.Trigger.signal trigger);
       Picos.Trigger.await trigger |> unwrap_;
+      if !closed_r then raise Closed;
       loop ()
   in
   loop ()
 
 let read fd buf i len : int =
-  retry_read_ fd (fun () ->
-      Trace_.message "read";
-      Unix.read fd buf i len)
+  try
+    retry_read_ fd (fun () ->
+        Trace_.message "read";
+        Unix.read fd buf i len)
+  with Closed -> 0
+
+let close fd =
+  Unix.close fd;
+  let ev = get_loop_exn_ () in
+  Nanoev.close ev fd
 
 let accept fd =
-  retry_read_ fd (fun () ->
-      Trace_.message "accept";
-      Unix.accept fd)
+  try
+    retry_read_ fd (fun () ->
+        Trace_.message "accept";
+        Unix.accept fd)
+  with Unix.Unix_error ((Unix.ESHUTDOWN | Unix.ECONNABORTED), _, _) ->
+    raise Closed
 
 let write fd buf i len : int =
-  retry_write_ fd (fun () ->
-      Trace_.message "write";
-      Unix.write fd buf i len)
+  try
+    retry_write_ fd (fun () ->
+        Trace_.message "write";
+        Unix.write fd buf i len)
+  with Closed -> 0
 
 let connect fd addr = retry_write_ fd (fun () -> Unix.connect fd addr)
 
diff --git a/src/picos/nanoev_picos.mli b/src/picos/nanoev_picos.mli
index 290e655..ef795bb 100644
--- a/src/picos/nanoev_picos.mli
+++ b/src/picos/nanoev_picos.mli
@@ -9,7 +9,24 @@ val has_bg_thread : unit -> bool
 (** {2 Non blocking IO primitives} *)
 
 val read : Unix.file_descr -> bytes -> int -> int -> int
-val connect : Unix.file_descr -> Unix.sockaddr -> unit
+(** Read from the non blocking FD.
+  @raise Nanoev.Closed if the FD is closed
+  @raise Unix.Unix_error for other errors *)
+
 val write : Unix.file_descr -> bytes -> int -> int -> int
+(** Write into the non blocking FD.
+  @raise Nanoev.Closed if the FD is closed
+  @raise Unix.Unix_error for other errors *)
+
+val close : Unix.file_descr -> unit
+(** Close the file descriptor
+  @raise Unix.Unix_error when it fails *)
+
+val connect : Unix.file_descr -> Unix.sockaddr -> unit
+
 val accept : Unix.file_descr -> Unix.file_descr * Unix.sockaddr
+(** Accept a connection on this fd.
+  @raise Nanoev.Closed if the FD is closed.
+  @raise Unix.Unix_error for other errors *)
+
 val sleep : float -> unit
diff --git a/src/tiny_httpd/nanoev_tiny_httpd.ml b/src/tiny_httpd/nanoev_tiny_httpd.ml
index ffcb7d4..3542c7b 100644
--- a/src/tiny_httpd/nanoev_tiny_httpd.ml
+++ b/src/tiny_httpd/nanoev_tiny_httpd.ml
@@ -77,13 +77,11 @@ module Out = struct
         done
 
       method private close_underlying () =
-        if not !closed then (
-          closed := true;
+        if not (Atomic.exchange closed true) then
           if close_noerr then (
-            try Unix.close fd with _ -> ()
+            try EV.close fd with _ -> ()
           ) else
-            Unix.close fd
-        )
+            EV.close fd
     end
 end
 
@@ -92,7 +90,6 @@ module In = struct
 
   class type t = In_buf.t
 
-  (* FIXME: closed should be atomic *)
   let of_unix_fd ?(close_noerr = false) ~closed ~(buf : Slice.t)
       (fd : Unix.file_descr) : t =
     let eof = ref false in
@@ -122,13 +119,12 @@ module In = struct
         )
 
       method close () =
-        if not !closed then (
-          closed := true;
+        if not (Atomic.exchange closed true) then (
           eof := true;
           if close_noerr then (
-            try Unix.close fd with _ -> ()
+            try EV.close fd with _ -> ()
           ) else
-            Unix.close fd
+            EV.close fd
         )
     end
 end
@@ -224,7 +220,7 @@ module Unix_tcp_server_ = struct
 
             Pool.with_resource self.slice_pool @@ fun ic_buf ->
             Pool.with_resource self.slice_pool @@ fun oc_buf ->
-            let closed = ref false in
+            let closed = Atomic.make false in
 
             let oc =
               new Out.of_unix_fd
diff --git a/src/unix/nanoev_unix.ml b/src/unix/nanoev_unix.ml
index 769c590..7d656c1 100644
--- a/src/unix/nanoev_unix.ml
+++ b/src/unix/nanoev_unix.ml
@@ -8,7 +8,7 @@ end
 (** Callback list *)
 type cbs =
   | Nil
-  | Sub : 'a * 'b * ('a -> 'b -> unit) * cbs -> cbs
+  | Sub : 'a * 'b * (closed:bool -> 'a -> 'b -> unit) * cbs -> cbs
 
 let[@inline] cb_is_empty = function
   | Nil -> true
@@ -44,6 +44,18 @@ type st = {
   lock: Mutex.t;
 }
 
+let rec perform_cbs ~closed = function
+  | Nil -> ()
+  | Sub (x, y, f, tail) ->
+    f ~closed x y;
+    perform_cbs ~closed tail
+
+let rec perform_cbs_closed ~closed = function
+  | Nil -> ()
+  | Sub (x, y, f, tail) ->
+    f ~closed x y;
+    perform_cbs_closed ~closed tail
+
 let leq_timer (Timer a) (Timer b) = a.deadline <= b.deadline
 
 let create_st () : st =
@@ -97,6 +109,25 @@ let get_fd_ (self : st) fd : per_fd =
     Hashtbl.add self.fds fd per_fd;
     per_fd
 
+let close self fd : unit =
+  let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.close" in
+  let r, w =
+    let@ self = with_lock_ self in
+    match Hashtbl.find self.fds fd with
+    | per_fd ->
+      Hashtbl.remove self.fds fd;
+      self.sub_up_to_date <- false;
+      if Atomic.get self.in_select then wakeup_from_outside self;
+      per_fd.r, per_fd.w
+    | exception Not_found ->
+      invalid_arg "File descriptor is not known to Nanoev"
+  in
+
+  (* call callbacks outside of the lock *)
+  perform_cbs_closed ~closed:true r;
+  perform_cbs_closed ~closed:true w;
+  ()
+
 let on_readable self fd x y f : unit =
   let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.on-readable" in
   let@ self = with_lock_ self in
@@ -140,12 +171,6 @@ let next_deadline_ (self : st) : float option =
   | exception Heap.Empty -> None
   | Timer t -> Some t.deadline
 
-let rec perform_cbs = function
-  | Nil -> ()
-  | Sub (x, y, f, tail) ->
-    f x y;
-    perform_cbs tail
-
 let step (self : st) : unit =
   let@ _sp = Trace_.with_span ~__FILE__ ~__LINE__ "nanoev.unix.step" in
   (* gather the subscriptions and timeout *)
@@ -207,19 +232,27 @@ let step (self : st) : unit =
   (* call callbacks *)
   List.iter
     (fun fd ->
-      perform_cbs fd.r;
+      perform_cbs ~closed:false fd.r;
       fd.r <- Nil)
     !ready_r;
   List.iter
     (fun fd ->
-      perform_cbs fd.w;
+      perform_cbs ~closed:false fd.w;
       fd.w <- Nil)
     !ready_w;
 
   ()
 
 let ops : st Nanoev.Impl.ops =
-  { step; on_readable; on_writable; run_after_s; wakeup_from_outside; clear }
+  {
+    step;
+    close;
+    on_readable;
+    on_writable;
+    run_after_s;
+    wakeup_from_outside;
+    clear;
+  }
 
 include Nanoev
 
diff --git a/tests/unix/t1.ml b/tests/unix/t1.ml
index 79e76ff..810087d 100644
--- a/tests/unix/t1.ml
+++ b/tests/unix/t1.ml
@@ -15,7 +15,11 @@ let () =
   let ev = E.create () in
   ignore (Thread.create loop ev : Thread.t);
   let rd, wr = mkpipe () in
-  E.on_readable ev rd () () (fun () () -> print_endline "can read");
+  E.on_readable ev rd () () (fun ~closed () () ->
+      if closed then
+        print_endline "closed!"
+      else
+        print_endline "can read");
   Thread.delay 0.05;
   print_endline "writing";
   ignore