diff -Naur samba-4.8.9/source3/winbindd/winbindd_util.c samba-4.8.9-fix_winbind_empty_domain/source3/winbindd/winbindd_util.c
--- samba-4.8.9/source3/winbindd/winbindd_util.c	2019-02-22 11:26:48.873478679 -0500
+++ samba-4.8.9-fix_winbind_empty_domain/source3/winbindd/winbindd_util.c	2019-02-22 11:25:57.075130007 -0500
@@ -1604,6 +1604,7 @@
 			fstrcpy(namespace, domain);
 		} else {
 			fstrcpy(namespace, lp_netbios_name());
+			fstrcpy(domain, namespace);
 		}
 	}