diff --git a/neofs/neofs_contract.go b/neofs/neofs_contract.go
index 4f2e405..2a612d3 100644
--- a/neofs/neofs_contract.go
+++ b/neofs/neofs_contract.go
@@ -34,7 +34,7 @@ const (
 	processingContractKey = "processingScriptHash"
 
 	maxBalanceAmount    = 9000 // Max integer of Fixed12 in JSON bound (2**53-1)
-	maxBalanceAmountGAS = maxBalanceAmount * 1_0000_0000
+	maxBalanceAmountGAS = int64(maxBalanceAmount) * 1_0000_0000
 
 	// hardcoded value to ignore deposit notification in onReceive
 	ignoreDepositNotification = "\x57\x0b"
@@ -241,7 +241,7 @@ func OnNEP17Payment(from interop.Hash160, amount int, data interface{}) {
 
 	if amount <= 0 {
 		common.AbortWithMessage("amount must be positive")
-	} else if maxBalanceAmountGAS < amount {
+	} else if maxBalanceAmountGAS < int64(amount) {
 		common.AbortWithMessage("out of max amount limit")
 	}
 
diff --git a/nns/namestate.go b/nns/namestate.go
index fb50f1d..72bbf94 100644
--- a/nns/namestate.go
+++ b/nns/namestate.go
@@ -9,13 +9,13 @@ import (
 type NameState struct {
 	Owner      interop.Hash160
 	Name       string
-	Expiration int
+	Expiration int64
 	Admin      interop.Hash160
 }
 
 // ensureNotExpired panics if domain name is expired.
 func (n NameState) ensureNotExpired() {
-	if runtime.GetTime() >= n.Expiration {
+	if int64(runtime.GetTime()) >= n.Expiration {
 		panic("name has expired")
 	}
 }
diff --git a/nns/nns_contract.go b/nns/nns_contract.go
index 54f1f55..1d0cf43 100644
--- a/nns/nns_contract.go
+++ b/nns/nns_contract.go
@@ -46,7 +46,7 @@ const (
 // Values constraints.
 const (
 	// maxRegisterPrice is the maximum price of register method.
-	maxRegisterPrice = 1_0000_0000_0000
+	maxRegisterPrice = int64(1_0000_0000_0000)
 	// maxRootLength is the maximum domain root length.
 	maxRootLength = 16
 	// maxDomainNameFragmentLength is the maximum length of the domain name fragment.
@@ -64,7 +64,7 @@ const (
 	// defaultRegisterPrice is the default price for new domain registration.
 	defaultRegisterPrice = 10_0000_0000
 	// millisecondsInYear is amount of milliseconds per year.
-	millisecondsInYear = 365 * 24 * 3600 * 1000
+	millisecondsInYear = int64(365 * 24 * 3600 * 1000)
 )
 
 // RecordState is a type that registered entities are saved to.
@@ -203,7 +203,7 @@ func Roots() iterator.Iterator {
 }
 
 // SetPrice sets the domain registration price.
-func SetPrice(price int) {
+func SetPrice(price int64) {
 	checkCommittee()
 	if price < 0 || price > maxRegisterPrice {
 		panic("The price is out of range.")
@@ -238,7 +238,7 @@ func IsAvailable(name string) bool {
 // parentExpired returns true if any domain from fragments doesn't exist or is expired.
 // first denotes the deepest subdomain to check.
 func parentExpired(ctx storage.Context, first int, fragments []string) bool {
-	now := runtime.GetTime()
+	now := int64(runtime.GetTime())
 	last := len(fragments) - 1
 	name := fragments[last]
 	for i := last; i >= first; i-- {
@@ -310,7 +310,7 @@ func Register(name string, owner interop.Hash160, email string, refresh, retry,
 	nsBytes := storage.Get(ctx, append([]byte{prefixName}, tokenKey...))
 	if nsBytes != nil {
 		ns := std.Deserialize(nsBytes.([]byte)).(NameState)
-		if runtime.GetTime() < ns.Expiration {
+		if int64(runtime.GetTime()) < ns.Expiration {
 			return false
 		}
 		oldOwner = ns.Owner
@@ -321,7 +321,7 @@ func Register(name string, owner interop.Hash160, email string, refresh, retry,
 	ns := NameState{
 		Owner:      owner,
 		Name:       name,
-		Expiration: runtime.GetTime() + millisecondsInYear,
+		Expiration: int64(runtime.GetTime()) + millisecondsInYear,
 	}
 	putNameStateWithKey(ctx, tokenKey, ns)
 	putSoaRecord(ctx, name, email, refresh, retry, expire, ttl)
@@ -331,7 +331,7 @@ func Register(name string, owner interop.Hash160, email string, refresh, retry,
 }
 
 // Renew increases domain expiration date.
-func Renew(name string) int {
+func Renew(name string) int64 {
 	if len(name) > maxDomainNameLength {
 		panic("invalid domain name format")
 	}
@@ -859,7 +859,7 @@ func tokenIDFromName(name string) string {
 		nsBytes := storage.Get(ctx, nameKey)
 		if nsBytes != nil {
 			ns := std.Deserialize(nsBytes.([]byte)).(NameState)
-			if runtime.GetTime() < ns.Expiration {
+			if int64(runtime.GetTime()) < ns.Expiration {
 				return name[sum:]
 			}
 		}