diff --git a/sys/bus/u4b/serial/usb_serial.c b/sys/bus/u4b/serial/usb_serial.c
index 1111111..2222222 100644
--- a/sys/bus/u4b/serial/usb_serial.c
+++ b/sys/bus/u4b/serial/usb_serial.c
@@ -1903,7 +1903,7 @@ ucom_get_data(struct ucom_softc *sc, struct usb_page_cache *pc,
 		}
 		/* copy data directly into USB buffer */
 		SET(tp->t_state, TS_BUSY);
-		cnt = clist_qtob(&tp->t_outq, res.buffer, len);
+		cnt = clist_qtob(&tp->t_outq, res.buffer, res.length);
 		if (cnt == 0) {
 			DPRINTF("ucom_get_data: cnt == 0\n");
 			CLR(tp->t_state, TS_BUSY);