peerconn.go | 2 +-

diff --git a/peerconn.go b/peerconn.go
index 633e54ce49a16658c7e16085dbf7fa7c43b04199..e333d21372b036d334e2769b429b904b55b638c8 100644
--- a/peerconn.go
+++ b/peerconn.go
@@ -663,7 +663,7 @@ 		}
 		if cn.writeBuffer.Len() == 0 {
 			cn.fillWriteBuffer()
 		}
-		if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout {
+		if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && cn.useful() {
 			cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
 			postedKeepalives.Add(1)
 		}