diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index f4a4f4ab5..e5a7a5519 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -1660,6 +1660,13 @@ func (bc *Blockchain) verifyResults(t *transaction.Transaction, results []*trans
 			if r.AssetID == UtilityTokenID() {
 				return errors.New("issue tx issues utility tokens")
 			}
+			asset, err := bc.dao.GetAssetState(r.AssetID)
+			if asset == nil || err != nil {
+				return errors.New("invalid asset in issue tx")
+			}
+			if asset.Available < r.Amount {
+				return errors.New("trying to issue more than available")
+			}
 		}
 		break
 	default:
@@ -1942,6 +1949,16 @@ func (bc *Blockchain) GetScriptHashesForVerifying(t *transaction.Transaction) ([
 	case transaction.EnrollmentType:
 		etx := t.Data.(*transaction.EnrollmentTX)
 		hashes[etx.PublicKey.GetScriptHash()] = true
+	case transaction.IssueType:
+		for _, res := range refsAndOutsToResults(references, t.Outputs) {
+			if res.Amount < 0 {
+				asset, err := bc.dao.GetAssetState(res.AssetID)
+				if asset == nil || err != nil {
+					return nil, errors.New("invalid asset in issue tx")
+				}
+				hashes[asset.Issuer] = true
+			}
+		}
 	case transaction.RegisterType:
 		reg := t.Data.(*transaction.RegisterTX)
 		hashes[reg.Owner.GetScriptHash()] = true
diff --git a/pkg/core/mempool/mem_pool.go b/pkg/core/mempool/mem_pool.go
index 5f9fe82ed..7dc38e2d4 100644
--- a/pkg/core/mempool/mem_pool.go
+++ b/pkg/core/mempool/mem_pool.go
@@ -168,7 +168,7 @@ func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
 	}
 	pItem.isLowPrio = fee.IsLowPriority(pItem.netFee)
 	mp.lock.Lock()
-	if !mp.verifyInputs(t) {
+	if !mp.checkTxConflicts(t) {
 		mp.lock.Unlock()
 		return ErrConflict
 	}
@@ -329,24 +329,39 @@ func (mp *Pool) GetVerifiedTransactions() []TxWithFee {
 	return t
 }
 
-// verifyInputs is an internal unprotected version of Verify.
-func (mp *Pool) verifyInputs(tx *transaction.Transaction) bool {
-	for i := range tx.Inputs {
-		n := findIndexForInput(mp.inputs, &tx.Inputs[i])
-		if n < len(mp.inputs) && *mp.inputs[n] == tx.Inputs[i] {
-			return false
+// areInputsInPool tries to find inputs in a given sorted pool and returns true
+// if it finds any.
+func areInputsInPool(inputs []transaction.Input, pool []*transaction.Input) bool {
+	for i := range inputs {
+		n := findIndexForInput(pool, &inputs[i])
+		if n < len(pool) && *pool[n] == inputs[i] {
+			return true
 		}
 	}
-	if tx.Type == transaction.ClaimType {
+	return false
+}
+
+// checkTxConflicts is an internal unprotected version of Verify.
+func (mp *Pool) checkTxConflicts(tx *transaction.Transaction) bool {
+	if areInputsInPool(tx.Inputs, mp.inputs) {
+		return false
+	}
+	switch tx.Type {
+	case transaction.ClaimType:
 		claim := tx.Data.(*transaction.ClaimTX)
-		for i := range claim.Claims {
-			n := findIndexForInput(mp.claims, &claim.Claims[i])
-			if n < len(mp.claims) && *mp.claims[n] == claim.Claims[i] {
+		if areInputsInPool(claim.Claims, mp.claims) {
+			return false
+		}
+	case transaction.IssueType:
+		// It's a hack, because technically we could check for
+		// available asset amount, but these transactions are so rare
+		// that no one really cares about this restriction.
+		for i := range mp.verifiedTxes {
+			if mp.verifiedTxes[i].txn.Type == transaction.IssueType {
 				return false
 			}
 		}
 	}
-
 	return true
 }
 
@@ -356,5 +371,5 @@ func (mp *Pool) verifyInputs(tx *transaction.Transaction) bool {
 func (mp *Pool) Verify(tx *transaction.Transaction) bool {
 	mp.lock.RLock()
 	defer mp.lock.RUnlock()
-	return mp.verifyInputs(tx)
+	return mp.checkTxConflicts(tx)
 }
diff --git a/pkg/core/mempool/mem_pool_test.go b/pkg/core/mempool/mem_pool_test.go
index 315361bb3..212a623f0 100644
--- a/pkg/core/mempool/mem_pool_test.go
+++ b/pkg/core/mempool/mem_pool_test.go
@@ -177,6 +177,31 @@ func TestMemPoolVerifyClaims(t *testing.T) {
 	require.Error(t, mp.Add(tx3, &FeerStub{}))
 }
 
+func TestMemPoolVerifyIssue(t *testing.T) {
+	mp := NewMemPool(50)
+	tx1 := newIssueTX()
+	require.Equal(t, true, mp.Verify(tx1))
+	require.NoError(t, mp.Add(tx1, &FeerStub{}))
+
+	tx2 := newIssueTX()
+	require.Equal(t, false, mp.Verify(tx2))
+	require.Error(t, mp.Add(tx2, &FeerStub{}))
+}
+
+func newIssueTX() *transaction.Transaction {
+	return &transaction.Transaction{
+		Type: transaction.IssueType,
+		Data: &transaction.IssueTX{},
+		Outputs: []transaction.Output{
+			transaction.Output{
+				AssetID:    random.Uint256(),
+				Amount:     util.Fixed8FromInt64(42),
+				ScriptHash: random.Uint160(),
+			},
+		},
+	}
+}
+
 func newMinerTX(i uint32) *transaction.Transaction {
 	return &transaction.Transaction{
 		Type: transaction.MinerType,