diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index d6e2bb49c59c..060dccb9ec75 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -197,7 +197,13 @@ static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
 			/* no data provider, so send silence */
 			unsigned int offs = 0;
 			for (i = 0; i < ctx->packets; ++i) {
-				int counts = ctx->packet_size[i];
+				int counts;
+
+				if (ctx->packet_size[i])
+					counts = ctx->packet_size[i];
+				else
+					counts = snd_usb_endpoint_next_packet_size(ep);
+
 				urb->iso_frame_desc[i].offset = offs * ep->stride;
 				urb->iso_frame_desc[i].length = counts * ep->stride;
 				offs += counts;