diff --git a/source3/passdb/lookup_sid.c b/source3/passdb/lookup_sid.c
index 5cf391f..701157c 100644
--- a/source3/passdb/lookup_sid.c
+++ b/source3/passdb/lookup_sid.c
@@ -1481,6 +1481,10 @@ bool sids_to_unix_ids(const struct dom_sid *sids, uint32_t num_sids,
 		if (ids[i].type != WBC_ID_TYPE_NOT_SPECIFIED) {
 			continue;
 		}
+		if ((ids[i].type == WBC_ID_TYPE_GID && ids[i].id.gid == -1)
+		   || (ids[i].type == WBC_ID_TYPE_UID && ids[i].id.uid == -1)) {
+			ids[i].type = WBC_ID_TYPE_NOT_SPECIFIED;
+		}
 		if (legacy_sid_to_gid(&sids[i], &ids[i].id.gid)) {
 			ids[i].type = WBC_ID_TYPE_GID;
 			continue;