diff --git a/pkg/core/blockchainer.go b/pkg/core/blockchainer.go
index 6ead1cd03..76c032c61 100644
--- a/pkg/core/blockchainer.go
+++ b/pkg/core/blockchainer.go
@@ -19,7 +19,6 @@ type Blockchainer interface {
 	AddHeaders(...*block.Header) error
 	AddBlock(*block.Block) error
 	AddStateRoot(r *state.MPTRoot) error
-	BlockHeight() uint32
 	CalculateClaimable(value util.Fixed8, startHeight, endHeight uint32) (util.Fixed8, util.Fixed8, error)
 	Close()
 	HeaderHeight() uint32
diff --git a/pkg/core/mempool/feer.go b/pkg/core/mempool/feer.go
index 89b63dab5..f425ddd2a 100644
--- a/pkg/core/mempool/feer.go
+++ b/pkg/core/mempool/feer.go
@@ -7,6 +7,7 @@ import (
 
 // Feer is an interface that abstract the implementation of the fee calculation.
 type Feer interface {
+	BlockHeight() uint32
 	NetworkFee(t *transaction.Transaction) util.Fixed8
 	IsLowPriority(util.Fixed8) bool
 	FeePerByte(t *transaction.Transaction) util.Fixed8
diff --git a/pkg/core/mempool/mem_pool.go b/pkg/core/mempool/mem_pool.go
index 7dc38e2d4..8f1895132 100644
--- a/pkg/core/mempool/mem_pool.go
+++ b/pkg/core/mempool/mem_pool.go
@@ -4,7 +4,6 @@ import (
 	"errors"
 	"sort"
 	"sync"
-	"time"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -26,7 +25,7 @@ var (
 // item represents a transaction in the the Memory pool.
 type item struct {
 	txn        *transaction.Transaction
-	timeStamp  time.Time
+	blockStamp uint32
 	perByteFee util.Fixed8
 	netFee     util.Fixed8
 	isLowPrio  bool
@@ -162,7 +161,7 @@ func dropInputFromSortedSlice(slice *[]*transaction.Input, input *transaction.In
 func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
 	var pItem = &item{
 		txn:        t,
-		timeStamp:  time.Now().UTC(),
+		blockStamp: fee.BlockHeight(),
 		perByteFee: fee.FeePerByte(t),
 		netFee:     fee.NetworkFee(t),
 	}
diff --git a/pkg/core/mempool/mem_pool_test.go b/pkg/core/mempool/mem_pool_test.go
index 5cfcf7b70..2d4059281 100644
--- a/pkg/core/mempool/mem_pool_test.go
+++ b/pkg/core/mempool/mem_pool_test.go
@@ -18,6 +18,10 @@ type FeerStub struct {
 	perByteFee  util.Fixed8
 }
 
+func (fs *FeerStub) BlockHeight() uint32 {
+	return 0
+}
+
 func (fs *FeerStub) NetworkFee(*transaction.Transaction) util.Fixed8 {
 	return fs.netFee
 }
diff --git a/pkg/rpc/server/server_helper_test.go b/pkg/rpc/server/server_helper_test.go
index 61bcc2e0d..9a84e44ce 100644
--- a/pkg/rpc/server/server_helper_test.go
+++ b/pkg/rpc/server/server_helper_test.go
@@ -85,6 +85,10 @@ func initServerWithInMemoryChain(t *testing.T) (*core.Blockchain, *Server, *http
 
 type FeerStub struct{}
 
+func (fs *FeerStub) BlockHeight() uint32 {
+	return 0
+}
+
 func (fs *FeerStub) NetworkFee(*transaction.Transaction) util.Fixed8 {
 	return 0
 }