diff --git a/dvb-core/dvb_ringbuffer.c b/dvb-core/dvb_ringbuffer.c
index 42f39af..60830ef 100644
--- a/dvb-core/dvb_ringbuffer.c
+++ b/dvb-core/dvb_ringbuffer.c
@@ -391,7 +391,9 @@ ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t*
 		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 	}
 
-	consumed = (idx - rbuf->pread) % rbuf->size;
+	consumed = idx - rbuf->pread;
+	if (consumed < 0)
+		consumed += rbuf->size;
 
 	while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {