diff --git a/lib/conduit_lwt_unix.ml b/lib/conduit_lwt_unix.ml
index 40f11a09..283257d7 100644
--- a/lib/conduit_lwt_unix.ml
+++ b/lib/conduit_lwt_unix.ml
@@ -318,10 +318,13 @@ let serve_with_default_tls ?timeout ?stop ~ctx ~certfile ~keyfile
                 ~pass ~port callback
   | No_tls -> failwith "No SSL or TLS support compiled into Conduit"
 
-let serve ?backlog ?timeout ?stop ~(ctx:ctx) ~(mode:server) callback =
-  let callback flow ic oc = Lwt.catch
+let serve ?backlog ?timeout ?stop
+    ?(on_exn=(fun exn -> !Lwt.async_exception_hook exn))
+    ~(ctx:ctx) ~(mode:server) callback =
+  let callback flow ic oc =
+    Lwt.catch
       (fun () -> callback flow ic oc)
-      (fun exn -> !Lwt.async_exception_hook exn; Lwt.return_unit)
+      (fun exn -> on_exn exn; Lwt.return_unit)
   in
   match mode with
   | `TCP (`Port port) ->
diff --git a/lib/conduit_lwt_unix.mli b/lib/conduit_lwt_unix.mli
index be19b012..fe12e80c 100644
--- a/lib/conduit_lwt_unix.mli
+++ b/lib/conduit_lwt_unix.mli
@@ -156,18 +156,19 @@ val init : ?src:string -> ?tls_server_key:tls_server_key -> unit -> ctx io
     via the [ctx] context to the endpoint described by [client] *)
 val connect : ctx:ctx -> client -> (flow * ic * oc) io
 
-(** [serve ?backlog ?timeout ?stop ~ctx ~mode fn] establishes a
-    listening connection of type [mode], using the [ctx] context.
-    The [stop] thread will terminate the server if it ever becomes
-    determined.  Every connection will be served in a new
-    lightweight thread that is invoked via the [fn] callback.
-    The [fn] callback is passed the {!flow} representing the
-    client connection and the associated input {!ic} and output
-    {!oc} channels. If the callback raises an exception, it is
-    passed to [!Lwt.async_exception_hook]. *)
+(** [serve ?backlog ?timeout ?stop ?on_exn ~ctx ~mode fn]
+    establishes a listening connection of type [mode], using the [ctx]
+    context.  The [stop] thread will terminate the server if it ever
+    becomes determined.  Every connection will be served in a new
+    lightweight thread that is invoked via the [fn] callback.  The
+    [fn] callback is passed the {!flow} representing the client
+    connection and the associated input {!ic} and output {!oc}
+    channels. If the callback raises an exception, it is passed to
+    [on_exn] (by default, to !Lwt.async_exception_hook). *)
 val serve :
-  ?backlog:int -> ?timeout:int -> ?stop:(unit io) -> ctx:ctx ->
-   mode:server -> (flow -> ic -> oc -> unit io) -> unit io
+  ?backlog:int -> ?timeout:int -> ?stop:(unit io) ->
+  ?on_exn:(exn -> unit) -> ctx:ctx -> mode:server ->
+  (flow -> ic -> oc -> unit io) -> unit io
 
 (** [endp_of_flow flow] retrieves the original {!Conduit.endp}
     from the established [flow] *)