diff --git a/common/collect/timed_queue.go b/common/collect/timed_queue.go
index 2943e7c57..1595723d6 100644
--- a/common/collect/timed_queue.go
+++ b/common/collect/timed_queue.go
@@ -36,6 +36,7 @@ func (queue *timedQueueImpl) Pop() interface{} {
 	old := *queue
 	n := len(old)
 	v := old[n-1]
+	old[n-1] = nil
 	*queue = old[:n-1]
 	return v
 }