diff --git a/src/adldap/samba/src_older/dom_sid.c b/src/adldap/samba/src_older/dom_sid.c
index 8884b445..96192773 100644
--- a/src/adldap/samba/src_older/dom_sid.c
+++ b/src/adldap/samba/src_older/dom_sid.c
@@ -584,3 +584,20 @@ char *dom_sid_str_buf(const struct dom_sid *sid, struct dom_sid_buf *dst)
 	}
 	return dst->buf;
 }
+
+// taken from libcli/security/util_sid.c
+
+void sid_copy(struct dom_sid *dst, const struct dom_sid *src)
+{
+	int i;
+
+	*dst = (struct dom_sid) {
+		.sid_rev_num = src->sid_rev_num,
+		.num_auths = src->num_auths,
+	};
+
+	memcpy(&dst->id_auth[0], &src->id_auth[0], sizeof(src->id_auth));
+
+	for (i = 0; i < src->num_auths; i++)
+		dst->sub_auths[i] = src->sub_auths[i];
+}