connection.go | 2 +-

diff --git a/connection.go b/connection.go
index 34737d6bbde12903d24a03f49fb6a8ed0c65b030..f4bef805698e119c04e68ee23ab5986df9b139d8 100644
--- a/connection.go
+++ b/connection.go
@@ -667,7 +667,7 @@ 	}
 }
 
 func (cn *connection) peerSentHave(piece int) error {
-	if cn.t.haveInfo() && piece >= cn.t.numPieces() {
+	if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
 		return errors.New("invalid piece")
 	}
 	if cn.PeerHasPiece(piece) {