webtorrent/tracker_client.go | 2 ++

diff --git a/webtorrent/tracker_client.go b/webtorrent/tracker_client.go
index c5aacaf25f36b7234d95fba430757bf48a29cbfb..0fe980c7a21c77b3ae11ad9f89f6c2f2ed353099 100644
--- a/webtorrent/tracker_client.go
+++ b/webtorrent/tracker_client.go
@@ -84,7 +84,9 @@ 	go func() {
 		for {
 			select {
 			case <-tc.pingTicker.C:
+				tc.mu.Lock()
 				err := c.WriteMessage(websocket.PingMessage, []byte{})
+				tc.mu.Unlock()
 				if err != nil {
 					return
 				}