diff --git a/core/txpool/list.go b/core/txpool/list.go
index ef1948e261..82c87b4263 100644
--- a/core/txpool/list.go
+++ b/core/txpool/list.go
@@ -46,6 +46,7 @@ func (h *nonceHeap) Pop() interface{} {
 	old := *h
 	n := len(old)
 	x := old[n-1]
+	old[n-1] = 0 // avoid memory leak
 	*h = old[0 : n-1]
 	return x
 }
diff --git a/core/types/transaction.go b/core/types/transaction.go
index 15f692458b..1e1cdeca6e 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -704,6 +704,7 @@ func (s *TxByPriceAndTime) Pop() interface{} {
 	old := s.txs
 	n := len(old)
 	x := old[n-1]
+	old[n-1] = nil // avoid memory leak
 	s.txs = old[0 : n-1]
 	return x
 }