diff --git a/subsys/bluetooth/host/conn.c b/subsys/bluetooth/host/conn.c
index 54e8e2cca1c..17ffb73b018 100644
--- a/subsys/bluetooth/host/conn.c
+++ b/subsys/bluetooth/host/conn.c
@@ -507,7 +507,8 @@ static int send_iso(struct bt_conn *conn, struct net_buf *buf, uint8_t flags)
 static inline uint16_t conn_mtu(struct bt_conn *conn)
 {
 #if defined(CONFIG_BT_BREDR)
-	if (conn->type == BT_CONN_TYPE_BR || !bt_dev.le.acl_mtu) {
+	if (conn->type == BT_CONN_TYPE_BR ||
+	    (conn->type != BT_CONN_TYPE_ISO && !bt_dev.le.acl_mtu)) {
 		return bt_dev.br.mtu;
 	}
 #endif /* CONFIG_BT_BREDR */