diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 9afb361437387bc412f5e8f9ac31660152c4da8b..7d42f61bd7ad962292bf7455858f0deed5551967 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1205,7 +1205,10 @@ static int change_speed(struct tty_struct *tty, struct usb_serial_port *port)
 	urb_index_value = get_ftdi_divisor(tty, port);
 	urb_value = (__u16)urb_index_value;
 	urb_index = (__u16)(urb_index_value >> 16);
-	if (priv->interface) {	/* FT2232C */
+	if ((priv->chip_type == FT2232C) || (priv->chip_type == FT2232H) ||
+		(priv->chip_type == FT4232H) || (priv->chip_type == FT232H)) {
+		/* Probably the BM type needs the MSB of the encoded fractional
+		 * divider also moved like for the chips above. Any infos? */
 		urb_index = (__u16)((urb_index << 8) | priv->interface);
 	}