diff --git a/samba/lib/com/dcom/main.c b/samba/lib/com/dcom/main.c
index a4e6691..94dbfaf 100644
--- a/samba/lib/com/dcom/main.c
+++ b/samba/lib/com/dcom/main.c
@@ -511,7 +511,7 @@ static struct composite_context *dcom_determine_rpc_binding(
     if (!NT_STATUS_IS_OK(status))
     {
         /* build a binding string using NCACN_IP_TCP */
-        char *bindstr = talloc_asprintf(c, "ncacn_ip_tcp:%s", server);
+        char *bindstr = talloc_asprintf(c, "ncacn_ip_tcp:%s[sign,seal]", server);
         if (composite_nomem(bindstr, c)) return c;
 
         status = dcerpc_parse_binding(c, bindstr, &activation_state->binding);