diff --git a/lib_eio/net.mli b/lib_eio/net.mli
index 6f7c6c8c3..b3acef262 100644
--- a/lib_eio/net.mli
+++ b/lib_eio/net.mli
@@ -175,6 +175,8 @@ val listen : ?reuse_addr:bool -> ?reuse_port:bool -> backlog:int -> sw:Switch.t
 
     The new socket will be closed when [sw] finishes, unless closed manually first.
 
+    On platforms that support this, passing port [0] will bind to a random port.
+
     For (non-abstract) Unix domain sockets, the path will be removed afterwards.
 
     @param backlog The number of pending connections that can be queued up (see listen(2)).