diff --git a/netmap/netmap_contract.go b/netmap/netmap_contract.go
index 7be60c1..fad4872 100644
--- a/netmap/netmap_contract.go
+++ b/netmap/netmap_contract.go
@@ -191,6 +191,7 @@ func UpdateInnerRing(keys []interop.PublicKey) {
 // by Alphabet node. If it was invoked by node candidate, it produces AddPeer
 // notification. Otherwise method throws panic.
 //
+// If the candidate already exists, it's info is updated.
 // NodeInfo argument contains stable marshaled version of netmap.NodeInfo
 // structure.
 func AddPeer(nodeInfo []byte) {
@@ -519,11 +520,6 @@ func addToNetmap(ctx storage.Context, n storageNode) {
 		}
 	)
 
-	data := storage.Get(ctx, storageKey)
-	if data != nil {
-		return
-	}
-
 	storage.Put(ctx, storageKey, std.Serialize(node))
 }
 
diff --git a/tests/basic.go b/tests/basic.go
index 6f36fa4..eb5e414 100644
--- a/tests/basic.go
+++ b/tests/basic.go
@@ -13,6 +13,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/fee"
 	"github.com/nspcc-dev/neo-go/pkg/core/native"
+	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
@@ -138,13 +139,14 @@ func DeployContract(t *testing.T, bc *core.Blockchain, path string, data interfa
 }
 
 // CheckHalt checks that transaction persisted with HALT state.
-func CheckHalt(t *testing.T, bc *core.Blockchain, h util.Uint256, stack ...stackitem.Item) {
+func CheckHalt(t *testing.T, bc *core.Blockchain, h util.Uint256, stack ...stackitem.Item) *state.AppExecResult {
 	aer, err := bc.GetAppExecResults(h, trigger.Application)
 	require.NoError(t, err)
 	require.Equal(t, vm.HaltState, aer[0].VMState, aer[0].FaultException)
 	if len(stack) != 0 {
 		require.Equal(t, stack, aer[0].Stack)
 	}
+	return &aer[0]
 }
 
 // CheckFault checks that transaction persisted with FAULT state.
diff --git a/tests/netmap_test.go b/tests/netmap_test.go
index cf9d472..c93831b 100644
--- a/tests/netmap_test.go
+++ b/tests/netmap_test.go
@@ -1,10 +1,14 @@
 package tests
 
 import (
+	"math/rand"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/core"
 	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/nspcc-dev/neo-go/pkg/wallet"
+	"github.com/stretchr/testify/require"
 )
 
 const netmapPath = "../netmap"
@@ -18,3 +22,59 @@ func deployNetmapContract(t *testing.T, bc *core.Blockchain, addrBalance, addrCo
 	args[4] = append([]interface{}{}, config...)
 	return DeployContract(t, bc, netmapPath, args)
 }
+
+func prepareNetmapContract(t *testing.T, bc *core.Blockchain) util.Uint160 {
+	addrNNS := DeployContract(t, bc, nnsPath, nil)
+
+	ctrNetmap, err := ContractInfo(CommitteeAcc.Contract.ScriptHash(), netmapPath)
+	require.NoError(t, err)
+
+	ctrBalance, err := ContractInfo(CommitteeAcc.Contract.ScriptHash(), balancePath)
+	require.NoError(t, err)
+
+	ctrContainer, err := ContractInfo(CommitteeAcc.Contract.ScriptHash(), containerPath)
+	require.NoError(t, err)
+
+	deployContainerContract(t, bc, ctrNetmap.Hash, ctrBalance.Hash, addrNNS)
+	deployBalanceContract(t, bc, ctrNetmap.Hash, ctrContainer.Hash)
+	return deployNetmapContract(t, bc, ctrBalance.Hash, ctrContainer.Hash, "ContainerFee", []byte{})
+}
+
+func dummyNodeInfo(acc *wallet.Account) []byte {
+	ni := make([]byte, 66)
+	rand.Read(ni)
+	copy(ni[2:], acc.PrivateKey().PublicKey().Bytes())
+	return ni
+}
+
+func TestAddPeer(t *testing.T) {
+	bc := NewChain(t)
+	h := prepareNetmapContract(t, bc)
+
+	acc := NewAccount(t, bc)
+	dummyInfo := dummyNodeInfo(acc)
+
+	acc1 := NewAccount(t, bc)
+	tx := PrepareInvoke(t, bc, acc1, h, "addPeer", dummyInfo)
+	AddBlock(t, bc, tx)
+	CheckFault(t, bc, tx.Hash(), "witness check failed")
+
+	tx = PrepareInvoke(t, bc, acc, h, "addPeer", dummyInfo)
+	AddBlock(t, bc, tx)
+
+	aer := CheckHalt(t, bc, tx.Hash())
+	require.Equal(t, 1, len(aer.Events))
+	require.Equal(t, "AddPeer", aer.Events[0].Name)
+	require.Equal(t, stackitem.NewArray([]stackitem.Item{stackitem.NewByteArray(dummyInfo)}),
+		aer.Events[0].Item)
+
+	dummyInfo[0] ^= 0xFF
+	tx = PrepareInvoke(t, bc, acc, h, "addPeer", dummyInfo)
+	AddBlock(t, bc, tx)
+
+	aer = CheckHalt(t, bc, tx.Hash())
+	require.Equal(t, 1, len(aer.Events))
+	require.Equal(t, "AddPeer", aer.Events[0].Name)
+	require.Equal(t, stackitem.NewArray([]stackitem.Item{stackitem.NewByteArray(dummyInfo)}),
+		aer.Events[0].Item)
+}