diff --git a/pkg/core/mem_pool.go b/pkg/core/mem_pool.go
index a01793a5d..2a629d403 100644
--- a/pkg/core/mem_pool.go
+++ b/pkg/core/mem_pool.go
@@ -287,23 +287,17 @@ func (mp *MemPool) GetVerifiedTransactions() []*transaction.Transaction {
 // If yes, the transaction tx is not a valid transaction and the function return false.
 // If no, the transaction tx is a valid transaction and the function return true.
 func (mp MemPool) Verify(tx *transaction.Transaction) bool {
-	count := 0
-	inputs := make([]*transaction.Input, 0)
-	for _, item := range mp.GetVerifiedTransactions() {
-		if tx.Hash().Equals(item.Hash()) {
-			for i := range item.Inputs {
-				inputs = append(inputs, &item.Inputs[i])
+	mp.lock.RLock()
+	defer mp.lock.RUnlock()
+	for _, item := range mp.unsortedTxn {
+		for i := range item.txn.Inputs {
+			for j := 0; j < len(tx.Inputs); j++ {
+				if item.txn.Inputs[i] == tx.Inputs[j] {
+					return false
+				}
 			}
 		}
 	}
 
-	for i := 0; i < len(inputs); i++ {
-		for j := 0; j < len(tx.Inputs); j++ {
-			if inputs[i].PrevHash.Equals(tx.Inputs[j].PrevHash) {
-				count++
-			}
-		}
-	}
-
-	return count == 0
+	return true
 }
diff --git a/pkg/core/mem_pool_test.go b/pkg/core/mem_pool_test.go
index bfd12230b..b75419d17 100644
--- a/pkg/core/mem_pool_test.go
+++ b/pkg/core/mem_pool_test.go
@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
+	"github.com/CityOfZion/neo-go/pkg/internal/random"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -62,3 +63,28 @@ func TestMemPoolAddRemove(t *testing.T) {
 	fs.lowPriority = true
 	t.Run("high priority", func(t *testing.T) { testMemPoolAddRemoveWithFeer(t, fs) })
 }
+
+func TestMemPoolVerify(t *testing.T) {
+	mp := NewMemPool(10)
+	tx := newMinerTX()
+	inhash1 := random.Uint256()
+	tx.Inputs = append(tx.Inputs, transaction.Input{PrevHash: inhash1, PrevIndex: 0})
+	require.Equal(t, true, mp.Verify(tx))
+	item := NewPoolItem(tx, &FeerStub{})
+	require.Equal(t, true, mp.TryAdd(tx.Hash(), item))
+
+	tx2 := newMinerTX()
+	inhash2 := random.Uint256()
+	tx2.Inputs = append(tx2.Inputs, transaction.Input{PrevHash: inhash2, PrevIndex: 0})
+	require.Equal(t, true, mp.Verify(tx2))
+	item = NewPoolItem(tx2, &FeerStub{})
+	require.Equal(t, true, mp.TryAdd(tx2.Hash(), item))
+
+	tx3 := newMinerTX()
+	// Different index number, but the same PrevHash as in tx1.
+	tx3.Inputs = append(tx3.Inputs, transaction.Input{PrevHash: inhash1, PrevIndex: 1})
+	require.Equal(t, true, mp.Verify(tx3))
+	// The same input as in tx2.
+	tx3.Inputs = append(tx3.Inputs, transaction.Input{PrevHash: inhash2, PrevIndex: 0})
+	require.Equal(t, false, mp.Verify(tx3))
+}