diff --git a/nns/nns_contract.go b/nns/nns_contract.go
index e34148f8..4f7f4faa 100644
--- a/nns/nns_contract.go
+++ b/nns/nns_contract.go
@@ -57,6 +57,9 @@ const (
 	maxDomainNameLength = 255
 	// maxTXTRecordLength is the maximum length of the TXT domain record.
 	maxTXTRecordLength = 255
+	// maxRecordID is the maximum value of record ID (the upper bound for the number
+	// of records with the same type).
+	maxRecordID = 255
 )
 
 // Other constants.
@@ -582,6 +585,9 @@ func addRecord(ctx storage.Context, tokenId []byte, name string, typ RecordType,
 			panic("record already exists")
 		}
 	}
+	if id > maxRecordID {
+		panic("maximum number of records reached")
+	}
 
 	if typ == CNAME && id != 0 {
 		panic("you shouldn't have more than one CNAME record")
diff --git a/tests/nns_test.go b/tests/nns_test.go
index 6b1b69d1..381217c7 100644
--- a/tests/nns_test.go
+++ b/tests/nns_test.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math/big"
 	"path"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -17,7 +18,10 @@ import (
 
 const nnsPath = "../nns"
 
-const msPerYear = 365 * 24 * time.Hour / time.Millisecond
+const (
+	msPerYear   = 365 * 24 * time.Hour / time.Millisecond
+	maxRecordID = 255 // value from the contract.
+)
 
 func newNNSInvoker(t *testing.T, addRoot bool) *neotest.ContractInvoker {
 	e := newExecutor(t)
@@ -400,3 +404,19 @@ func TestNNSResolve(t *testing.T) {
 	// Empty result.
 	c.Invoke(t, stackitem.NewArray([]stackitem.Item{}), "resolve", "test.com", int64(nns.CNAME))
 }
+
+func TestNNSAddRecord(t *testing.T) {
+	c := newNNSInvoker(t, true)
+
+	refresh, retry, expire, ttl := int64(101), int64(102), int64(103), int64(104)
+	c.Invoke(t, true, "register",
+		"testdomain.com", c.CommitteeHash,
+		"myemail@nspcc.ru", refresh, retry, expire, ttl)
+	for i := 0; i <= maxRecordID+1; i++ {
+		if i == maxRecordID+1 {
+			c.InvokeFail(t, "maximum number of records reached", "addRecord", "testdomain.com", int64(nns.TXT), strconv.Itoa(i))
+		} else {
+			c.Invoke(t, stackitem.Null{}, "addRecord", "testdomain.com", int64(nns.TXT), strconv.Itoa(i))
+		}
+	}
+}