peer_protocol/protocol.go | 5 +++++
 peerconn.go               | 2 ++

diff --git a/peer_protocol/protocol.go b/peer_protocol/protocol.go
index bfeb6a0448873da8b3fdc96dd133520da0c8d360..2f92ab324d2315abd7b8d483767a9b0c1080ab70 100644
--- a/peer_protocol/protocol.go
+++ b/peer_protocol/protocol.go
@@ -41,6 +41,11 @@ 	AllowedFast MessageType = 0x11 // 17
 
 	// BEP 10
 	Extended MessageType = 20
+
+	// BEP 52
+	HashRequest = 21
+	Hashes      = 22
+	HashReject  = 23
 )
 
 const (
diff --git a/peerconn.go b/peerconn.go
index a1e98b1282ac040780c8df05aadaf3bb42226ccc..ded9b483e5f5eaccdc0e24e5480788c93cf55443 100644
--- a/peerconn.go
+++ b/peerconn.go
@@ -862,6 +862,8 @@ 			log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).LogLevel(log.Debug, c.t.logger)
 			c.updateRequests("PeerConn.mainReadLoop allowed fast")
 		case pp.Extended:
 			err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
+		case pp.HashRequest, pp.Hashes, pp.HashReject:
+			err = log.WithLevel(log.Warning, fmt.Errorf("received unimplemented BitTorrent v2 message: %v", msg.Type))
 		default:
 			err = fmt.Errorf("received unknown message type: %#v", msg.Type)
 		}