diff --git a/.golangci.yml b/.golangci.yml
index d63fe3d3e..4c282cb30 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -47,6 +47,7 @@ linters:
     - errorlint
     - gofmt
     - misspell
+    - predeclared
     - whitespace
     - goimports
   disable-all: true
diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index 479f5a83d..1c14b7851 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -693,15 +693,15 @@ func (bc *Blockchain) Run() {
 	}
 }
 
-func (bc *Blockchain) tryRunGC(old uint32) time.Duration {
+func (bc *Blockchain) tryRunGC(oldHeight uint32) time.Duration {
 	var dur time.Duration
 
-	new := atomic.LoadUint32(&bc.persistedHeight)
-	var tgtBlock = int64(new)
+	newHeight := atomic.LoadUint32(&bc.persistedHeight)
+	var tgtBlock = int64(newHeight)
 
 	tgtBlock -= int64(bc.config.MaxTraceableBlocks)
 	if bc.config.P2PStateExchangeExtensions {
-		syncP := new / uint32(bc.config.StateSyncInterval)
+		syncP := newHeight / uint32(bc.config.StateSyncInterval)
 		syncP--
 		syncP *= uint32(bc.config.StateSyncInterval)
 		if tgtBlock > int64(syncP) {
@@ -712,9 +712,9 @@ func (bc *Blockchain) tryRunGC(old uint32) time.Duration {
 	tgtBlock /= int64(bc.config.GarbageCollectionPeriod)
 	tgtBlock *= int64(bc.config.GarbageCollectionPeriod)
 	// Count periods.
-	old /= bc.config.GarbageCollectionPeriod
-	new /= bc.config.GarbageCollectionPeriod
-	if tgtBlock > int64(bc.config.GarbageCollectionPeriod) && new != old {
+	oldHeight /= bc.config.GarbageCollectionPeriod
+	newHeight /= bc.config.GarbageCollectionPeriod
+	if tgtBlock > int64(bc.config.GarbageCollectionPeriod) && newHeight != oldHeight {
 		tgtBlock /= int64(bc.config.GarbageCollectionPeriod)
 		tgtBlock *= int64(bc.config.GarbageCollectionPeriod)
 		dur = bc.stateRoot.GC(uint32(tgtBlock), bc.store)
diff --git a/pkg/core/dao/dao.go b/pkg/core/dao/dao.go
index 5e1f17960..cd8266bef 100644
--- a/pkg/core/dao/dao.go
+++ b/pkg/core/dao/dao.go
@@ -828,14 +828,14 @@ func (dao *Simple) StoreAsTransaction(tx *transaction.Transaction, index uint32,
 	return nil
 }
 
-func (dao *Simple) getKeyBuf(len int) []byte {
+func (dao *Simple) getKeyBuf(l int) []byte {
 	if dao.private {
 		if dao.keyBuf == nil {
 			dao.keyBuf = make([]byte, 0, 1+4+limits.MaxStorageKeyLen) // Prefix, uint32, key.
 		}
-		return dao.keyBuf[:len] // Should have enough capacity.
+		return dao.keyBuf[:l] // Should have enough capacity.
 	}
-	return make([]byte, len)
+	return make([]byte, l)
 }
 
 func (dao *Simple) getDataBuf() *io.BufBinWriter {
diff --git a/pkg/neorpc/result/validator_test.go b/pkg/neorpc/result/validator_test.go
index f7ecd4b68..a45a81523 100644
--- a/pkg/neorpc/result/validator_test.go
+++ b/pkg/neorpc/result/validator_test.go
@@ -13,8 +13,8 @@ func TestValidatorUnmarshal(t *testing.T) {
 	require.NoError(t, json.Unmarshal(old, v))
 	require.Equal(t, int64(100500), v.Votes)
 
-	new := []byte(`{"publickey":"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62","votes":42}`)
-	require.NoError(t, json.Unmarshal(new, v))
+	newV := []byte(`{"publickey":"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62","votes":42}`)
+	require.NoError(t, json.Unmarshal(newV, v))
 	require.Equal(t, int64(42), v.Votes)
 
 	bad := []byte(`{"publickey":"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62","votes":"notanumber"}`)