diff --git a/nns/nns_contract.go b/nns/nns_contract.go
index 202a03d..6ef39d1 100644
--- a/nns/nns_contract.go
+++ b/nns/nns_contract.go
@@ -52,7 +52,7 @@ const (
 	// maxDomainNameFragmentLength is the maximum length of the domain name fragment.
 	maxDomainNameFragmentLength = 63
 	// minDomainNameLength is minimum domain length.
-	minDomainNameLength = 3
+	minDomainNameLength = 2
 	// maxDomainNameLength is maximum domain length.
 	maxDomainNameLength = 255
 	// maxTXTRecordLength is the maximum length of the TXT domain record.
diff --git a/tests/nns_test.go b/tests/nns_test.go
index 7ee43ae..6eeb3b6 100644
--- a/tests/nns_test.go
+++ b/tests/nns_test.go
@@ -58,6 +58,16 @@ func TestNNSRegisterTLD(t *testing.T) {
 		"com", acc.ScriptHash(),
 		"email@frostfs.info", refresh, retry, expire, ttl)
 
+	t.Run("size checks", func(t *testing.T) {
+		c.Invoke(t, true, "register",
+			"ns", c.CommitteeHash,
+			"email@frostfs.info", refresh, retry, expire, ttl)
+
+		c.InvokeFail(t, "invalid domain name format", "register",
+			"x", c.CommitteeHash,
+			"email@frostfs.info", refresh, retry, expire, ttl)
+	})
+
 	c.Invoke(t, true, "register",
 		"com", c.CommitteeHash,
 		"email@frostfs.info", refresh, retry, expire, ttl)