client.go | 3 +++

diff --git a/client.go b/client.go
index 9fe3f39dcdce81f0480278037d0394d994f568af..23ebe86b7607bfef432a5c09f61ae84aa0f322c2 100644
--- a/client.go
+++ b/client.go
@@ -1008,6 +1008,9 @@ 	}
 newAnnounce:
 	for {
 		cl.mu.Lock()
+		if t.isClosed() {
+			return
+		}
 		req.Left = t.BytesLeft()
 		cl.mu.Unlock()
 		for _, tier := range t.Trackers {