diff --git a/options.c b/options.c
index 5f1efc5d..6d3ef8e5 100644
--- a/options.c
+++ b/options.c
@@ -4258,7 +4258,7 @@ add_option (struct options *options,
 
       VERIFY_PERMISSION (OPT_P_GENERAL|OPT_P_CONNECTION);
       port = atoi (p[1]);
-      if (!legal_ipv4_port (port))
+      if ((port != 0) && !legal_ipv4_port (port))
 	{
 	  msg (msglevel, "Bad local port number: %s", p[1]);
 	  goto err;