diff --git a/core/tx_list.go b/core/tx_list.go
index bf304eedcf43..cdd3df14c5b0 100644
--- a/core/tx_list.go
+++ b/core/tx_list.go
@@ -433,6 +433,7 @@ func (h *priceHeap) Pop() interface{} {
 	old := *h
 	n := len(old)
 	x := old[n-1]
+	old[n-1] = nil
 	*h = old[0 : n-1]
 	return x
 }