diff --git a/src/ws/tiny_httpd_ws.ml b/src/ws/tiny_httpd_ws.ml
index 81d452cc..d278e919 100644
--- a/src/ws/tiny_httpd_ws.ml
+++ b/src/ws/tiny_httpd_ws.ml
@@ -76,12 +76,7 @@ module Writer = struct
       Mutex.unlock self.mutex;
       raise e
 
-  let close self =
-    if not self.closed then (
-      self.closed <- true;
-      raise Close_connection
-    )
-
+  let[@inline] close self = self.closed <- true
   let int_of_bool : bool -> int = Obj.magic
 
   (** Write the frame header to [self.oc] *)
diff --git a/src/ws/tiny_httpd_ws.mli b/src/ws/tiny_httpd_ws.mli
index 77e71232..bb63f992 100644
--- a/src/ws/tiny_httpd_ws.mli
+++ b/src/ws/tiny_httpd_ws.mli
@@ -10,6 +10,10 @@ type handler = unit Request.t -> IO.Input.t -> IO.Output.t -> unit
 val upgrade : IO.Input.t -> IO.Output.t -> IO.Input.t * IO.Output.t
 (** Upgrade a byte stream to the websocket framing protocol. *)
 
+exception Close_connection
+(** Exception that can be raised from IOs inside the handler,
+    when the connection is closed from underneath. *)
+
 val add_route_handler :
   ?accept:(unit Request.t -> (unit, int * string) result) ->
   ?accept_ws_protocol:(string -> bool) ->