diff --git a/pkg/core/blockchain_test.go b/pkg/core/blockchain_test.go
index 033769ef5..810c77622 100644
--- a/pkg/core/blockchain_test.go
+++ b/pkg/core/blockchain_test.go
@@ -86,7 +86,7 @@ func TestGetHeader(t *testing.T) {
 
 	block = newBlock(2)
 	hash = block.Hash()
-	_, err = bc.getHeader(block.Hash())
+	_, err = bc.getHeader(hash)
 	assert.NotNil(t, err)
 }
 
diff --git a/pkg/core/storage/helpers.go b/pkg/core/storage/helpers.go
index 6ba5b97a1..88dde7a5a 100644
--- a/pkg/core/storage/helpers.go
+++ b/pkg/core/storage/helpers.go
@@ -63,7 +63,7 @@ func HeaderHashes(s Store) ([]util.Uint256, error) {
 	})
 
 	var (
-		hashes     []util.Uint256
+		hashes     = make([]util.Uint256, 0, len(hashMap))
 		sortedKeys = make([]uint32, 0, len(hashMap))
 	)
 
diff --git a/pkg/network/tcp_transport.go b/pkg/network/tcp_transport.go
index a9c1b4cd3..82ea5f351 100644
--- a/pkg/network/tcp_transport.go
+++ b/pkg/network/tcp_transport.go
@@ -15,6 +15,8 @@ type TCPTransport struct {
 	bindAddr string
 }
 
+var reClosedNetwork = regexp.MustCompile(".* use of closed network connection")
+
 // NewTCPTransport return a new TCPTransport that will listen for
 // new incoming peer connections.
 func NewTCPTransport(s *Server, bindAddr string) *TCPTransport {
@@ -58,13 +60,8 @@ func (t *TCPTransport) Accept() {
 }
 
 func (t *TCPTransport) isCloseError(err error) bool {
-	regex, err := regexp.Compile(".* use of closed network connection")
-	if err != nil {
-		return false
-	}
-
 	if opErr, ok := err.(*net.OpError); ok {
-		if regex.Match([]byte(opErr.Error())) {
+		if reClosedNetwork.Match([]byte(opErr.Error())) {
 			return true
 		}
 	}
diff --git a/pkg/rpc/neoScanBalanceGetter.go b/pkg/rpc/neoScanBalanceGetter.go
index dcc01bf84..6bd243042 100644
--- a/pkg/rpc/neoScanBalanceGetter.go
+++ b/pkg/rpc/neoScanBalanceGetter.go
@@ -52,7 +52,7 @@ func filterSpecificAsset(asset string, balance []*Unspent, assetBalance *Unspent
 func (s NeoScanServer) CalculateInputs(address string, assetIdUint util.Uint256, cost util.Fixed8) ([]transaction.Input, util.Fixed8, error) {
 	var (
 		err          error
-		num, i       = uint16(0), uint16(0)
+		num, i       uint16
 		required     = cost
 		selected     = util.Fixed8(0)
 		us           []*Unspent
diff --git a/pkg/rpc/stack_param_test.go b/pkg/rpc/stack_param_test.go
index 0dbe2997d..e1fd8a60d 100644
--- a/pkg/rpc/stack_param_test.go
+++ b/pkg/rpc/stack_param_test.go
@@ -114,6 +114,10 @@ const (
 func TestStackParam_TryParse(t *testing.T) {
 	// ByteArray to util.Uint160 conversion
 	data, err := hex.DecodeString(hash160)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	var (
 		outputUint160, expectedUint160 util.Uint160
 		input                          = StackParam{
@@ -122,6 +126,9 @@ func TestStackParam_TryParse(t *testing.T) {
 		}
 	)
 	expectedUint160, err = util.Uint160DecodeString(hash160)
+	if err != nil {
+		t.Fatal(err)
+	}
 	if err = input.TryParse(&outputUint160); err != nil {
 		t.Errorf("failed to parse stackparam to Uint160: %v", err)
 	}
@@ -131,6 +138,10 @@ func TestStackParam_TryParse(t *testing.T) {
 
 	// ByteArray to util.Uint256 conversion
 	data, err = hex.DecodeString(hash256)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	var (
 		outputUint256, expectedUint256 util.Uint256
 		uint256input                   = StackParam{
@@ -139,6 +150,9 @@ func TestStackParam_TryParse(t *testing.T) {
 		}
 	)
 	expectedUint256, err = util.Uint256DecodeString(hash256)
+	if err != nil {
+		t.Fatal(err)
+	}
 	if err = uint256input.TryParse(&outputUint256); err != nil {
 		t.Errorf("failed to parse stackparam to []byte: %v", err)
 	}
@@ -160,6 +174,9 @@ func TestStackParam_TryParse(t *testing.T) {
 
 	// ByteArray to int64 conversion
 	data, err = hex.DecodeString("637829cd0b")
+	if err != nil {
+		t.Fatal(err)
+	}
 	var (
 		outputInt, expectedInt int64
 		intinput               = StackParam{
@@ -194,7 +211,13 @@ func TestStackParam_TryParse(t *testing.T) {
 
 	// StackParams to []util.Uint160
 	data, err = hex.DecodeString(hash160)
+	if err != nil {
+		t.Fatal(err)
+	}
 	expUint160, err := util.Uint160DecodeString(hash160)
+	if err != nil {
+		t.Fatal(err)
+	}
 	var (
 		params = StackParams{
 			StackParam{
diff --git a/pkg/util/array_test.go b/pkg/util/array_test.go
index dae4fc65a..f8d78c979 100644
--- a/pkg/util/array_test.go
+++ b/pkg/util/array_test.go
@@ -9,7 +9,7 @@ func TestArrayReverse(t *testing.T) {
 	arr := []byte{0x01, 0x02, 0x03, 0x04, 0x05}
 	have := ArrayReverse(arr)
 	want := []byte{0x05, 0x04, 0x03, 0x02, 0x01}
-	if bytes.Compare(have, want) != 0 {
+	if !bytes.Equal(have, want) {
 		t.Fatalf("expected %v got %v", want, have)
 	}
 }
@@ -19,7 +19,7 @@ func TestArrayReverseLen2(t *testing.T) {
 	arr := []byte{0x01}
 	have := ArrayReverse(arr)
 	want := []byte{0x01}
-	if bytes.Compare(have, want) != 0 {
+	if !bytes.Equal(have, want) {
 		t.Fatalf("expected %v got %v", want, have)
 	}
 }
diff --git a/pkg/util/io.go b/pkg/util/io.go
index 21beccb97..fcc737a73 100644
--- a/pkg/util/io.go
+++ b/pkg/util/io.go
@@ -3,7 +3,6 @@ package util
 import (
 	"bytes"
 	"encoding/binary"
-	"errors"
 	"io"
 )
 
@@ -39,9 +38,6 @@ func ReadVarUint(r io.Reader) uint64 {
 
 // WriteVarUint writes a variable unsigned integer.
 func WriteVarUint(w io.Writer, val uint64) error {
-	if val < 0 {
-		return errors.New("value out of range")
-	}
 	if val < 0xfd {
 		return binary.Write(w, binary.LittleEndian, uint8(val))
 	}
diff --git a/pkg/util/uint160.go b/pkg/util/uint160.go
index 9e7973265..84251841f 100644
--- a/pkg/util/uint160.go
+++ b/pkg/util/uint160.go
@@ -74,9 +74,7 @@ func (u *Uint160) UnmarshalJSON(data []byte) (err error) {
 	if err = json.Unmarshal(data, &js); err != nil {
 		return err
 	}
-	if strings.HasPrefix(js, "0x") {
-		js = js[2:]
-	}
+	js = strings.TrimPrefix(js, "0x")
 	*u, err = Uint160DecodeString(js)
 	return err
 }
diff --git a/pkg/util/uint256.go b/pkg/util/uint256.go
index 69e0c1b6b..4a699c890 100644
--- a/pkg/util/uint256.go
+++ b/pkg/util/uint256.go
@@ -60,9 +60,7 @@ func (u *Uint256) UnmarshalJSON(data []byte) (err error) {
 	if err = json.Unmarshal(data, &js); err != nil {
 		return err
 	}
-	if strings.HasPrefix(js, "0x") {
-		js = js[2:]
-	}
+	js = strings.TrimPrefix(js, "0x")
 	*u, err = Uint256DecodeString(js)
 	return err
 }
diff --git a/pkg/vm/compiler/codegen.go b/pkg/vm/compiler/codegen.go
index 8f482e399..df77461e1 100644
--- a/pkg/vm/compiler/codegen.go
+++ b/pkg/vm/compiler/codegen.go
@@ -757,9 +757,6 @@ func (c *codegen) writeJumps() {
 				continue
 			}
 			offset := uint16(c.l[index] - i)
-			if offset < 0 {
-				log.Fatalf("new offset is negative, table list %v", c.l)
-			}
 			binary.LittleEndian.PutUint16(b[j:j+2], offset)
 		}
 	}
diff --git a/pkg/vm/state_test.go b/pkg/vm/state_test.go
index f1d2154f1..0b4dc64f7 100644
--- a/pkg/vm/state_test.go
+++ b/pkg/vm/state_test.go
@@ -37,7 +37,7 @@ func TestStateFromString(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, faultState|breakState, s)
 
-	s, err = StateFromString("HALT, KEK")
+	_, err = StateFromString("HALT, KEK")
 	assert.Error(t, err)
 }
 
diff --git a/pkg/wallet/nep2.go b/pkg/wallet/nep2.go
index b9409fc03..651567a9c 100644
--- a/pkg/wallet/nep2.go
+++ b/pkg/wallet/nep2.go
@@ -125,7 +125,7 @@ func compareAddressHash(priv *PrivateKey, hash []byte) bool {
 		return false
 	}
 	addrHash := hashAddress(address)[0:4]
-	return bytes.Compare(addrHash, hash) == 0
+	return bytes.Equal(addrHash, hash)
 }
 
 func validateNEP2Format(b []byte) error {