torrent.go | 9 ++++++++-

diff --git a/torrent.go b/torrent.go
index 1eb237e8008e4538c39097068d21a79e987c5092..419375174c2ccdf4caaf66fc9138d510f5fdda2d 100644
--- a/torrent.go
+++ b/torrent.go
@@ -999,7 +999,14 @@ 	prio, ok := t.pendingPieces.GetPriority(piece)
 	if !ok {
 		return PiecePriorityNone
 	}
-	return piecePriority(-prio)
+	if prio > 0 {
+		panic(prio)
+	}
+	ret := piecePriority(-prio)
+	if ret == PiecePriorityNone {
+		panic(piece)
+	}
+	return ret
 }
 
 func (t *Torrent) pendRequest(req request) {