diff --git a/source3/passdb/lookup_sid.c b/source3/passdb/lookup_sid.c
index 5cf391f..553bbd6 100644
--- a/source3/passdb/lookup_sid.c
+++ b/source3/passdb/lookup_sid.c
@@ -1490,7 +1490,14 @@ bool sids_to_unix_ids(const struct dom_sid *sids, uint32_t num_sids,
 			continue;
 		}
 	}
+
 done:
+	for (i=0; i<num_sids; i++) {
+		if ((ids[i].type == WBC_ID_TYPE_GID && ids[i].id.gid == (gid_t)-1)
+		   || (ids[i].type == WBC_ID_TYPE_UID && ids[i].id.uid == (uid_t)-1)) {
+			ids[i].type = WBC_ID_TYPE_NOT_SPECIFIED;
+		}
+	}
 	ret = true;
 fail:
 	TALLOC_FREE(wbc_ids);