diff --git a/collects/scribblings/reference/networking.scrbl b/collects/scribblings/reference/networking.scrbl
index 562fb76e52..e241ea210e 100644
--- a/collects/scribblings/reference/networking.scrbl
+++ b/collects/scribblings/reference/networking.scrbl
@@ -293,7 +293,8 @@ non-@racket[#f], then the socket's protocol family is IPv4.}
 @defproc[(udp-bind! [udp-socket udp?]
                     [hostname-string (or/c string? #f)]
                     [port-no (and/c exact-nonnegative-integer?
-                                    (integer-in 0 65535))])
+                                    (integer-in 0 65535))]
+		    [reuse? any/c #f])
          void?]{
 
 Binds an unbound @racket[udp-socket] to the local port number
@@ -325,8 +326,12 @@ socket is later used again in a send, then the later send may change
 the socket's automatic binding.
 
 If @racket[udp-socket] is already bound or closed, the
-@exnraise[exn:fail:network].}
+@exnraise[exn:fail:network].
 
+If the @racket[reuse?] argument is true, then @racket[udp-bind!] will
+set the @tt{SO_REUSEADDR} socket option before binding, permitting the
+sharing of access to a UDP port between many processes on a single
+machine when using UDP multicast.}
 
 @defproc[(udp-connect! [udp-socket udp?]
                        [hostname-string (or/c string? #f)]
diff --git a/src/racket/src/network.c b/src/racket/src/network.c
index b64d8ca6ad..0a045dba08 100644
--- a/src/racket/src/network.c
+++ b/src/racket/src/network.c
@@ -269,7 +269,7 @@ void scheme_init_network(Scheme_Env *env)
   GLOBAL_FOLDING_PRIM  ( "udp?"                      , udp_p                    , 1 , 1 , 1 , netenv ) ;
   GLOBAL_PRIM_W_ARITY  ( "udp-bound?"                , udp_bound_p              , 1 , 1 , netenv ) ;
   GLOBAL_PRIM_W_ARITY  ( "udp-connected?"            , udp_connected_p          , 1 , 1 , netenv ) ;
-  GLOBAL_PRIM_W_ARITY  ( "udp-bind!"                 , udp_bind                 , 3 , 3 , netenv ) ;
+  GLOBAL_PRIM_W_ARITY  ( "udp-bind!"                 , udp_bind                 , 3 , 4 , netenv ) ;
   GLOBAL_PRIM_W_ARITY  ( "udp-connect!"              , udp_connect              , 3 , 3 , netenv ) ;
 
   GLOBAL_PRIM_W_ARITY  ( "udp-send-to"               , udp_send_to              , 4 , 6 , netenv ) ;
@@ -3276,6 +3276,19 @@ static Scheme_Object *udp_bind_or_connect(const char *name, int argc, Scheme_Obj
     /* BIND CASE */
     else {
       int ok;
+
+      if ((argc > 3) && SCHEME_TRUEP(argv[3])) {
+	int one = 1;
+	if (setsockopt(udp->s, SOL_SOCKET, SO_REUSEADDR, (void *) &one, sizeof(one))) {
+	  scheme_raise_exn(MZEXN_FAIL_NETWORK,
+			   "%s: can't set SO_REUSEADDR\n"
+			   "  system error: %E",
+			   name,
+			   SOCK_ERRNO());
+	  return NULL;
+	}
+      }
+
       if (udp_bind_addr == NULL ) {
         GC_CAN_IGNORE mz_unspec_address ua;
         memset(&ua, 0, sizeof(mz_unspec_address));