diff --git a/jsonrpc/service.go b/jsonrpc/service.go
index 11b2804..7fc925b 100644
--- a/jsonrpc/service.go
+++ b/jsonrpc/service.go
@@ -35,6 +35,7 @@ import (
 
 // Service is an Starknet client service.
 type Service struct {
+	log              zerolog.Logger
 	base             *url.URL
 	address          string
 	webSocketAddress string
@@ -47,9 +48,6 @@ type Service struct {
 	connectionSynced bool
 }
 
-// log is a service-wide logger.
-var log zerolog.Logger
-
 // New creates a new execution client service, connecting with a standard HTTP.
 func New(ctx context.Context, params ...Parameter) (*Service, error) {
 	parameters, err := parseAndCheckParameters(params...)
@@ -58,7 +56,7 @@ func New(ctx context.Context, params ...Parameter) (*Service, error) {
 	}
 
 	// Set logging.
-	log = zerologger.With().Str("service", "client").Str("impl", "jsonrpc").Logger()
+	log := zerologger.With().Str("service", "client").Str("impl", "jsonrpc").Logger()
 	if parameters.logLevel != log.GetLevel() {
 		log = log.Level(parameters.logLevel)
 	}
@@ -109,6 +107,7 @@ func New(ctx context.Context, params ...Parameter) (*Service, error) {
 	})
 
 	s := &Service{
+		log:              log,
 		base:             base,
 		client:           rpcClient,
 		address:          address.String(),
diff --git a/jsonrpc/service_test.go b/jsonrpc/service_test.go
index 9e6c7ff..50e1d8e 100644
--- a/jsonrpc/service_test.go
+++ b/jsonrpc/service_test.go
@@ -42,6 +42,7 @@ func TestService(t *testing.T) {
 		{
 			name: "AddressNil",
 			parameters: []jsonrpc.Parameter{
+				jsonrpc.WithLogLevel(zerolog.Disabled),
 				jsonrpc.WithTimeout(5 * time.Second),
 			},
 			err: "no address specified",
@@ -49,6 +50,7 @@ func TestService(t *testing.T) {
 		{
 			name: "TimeoutZero",
 			parameters: []jsonrpc.Parameter{
+				jsonrpc.WithLogLevel(zerolog.Disabled),
 				jsonrpc.WithAddress(os.Getenv("JSONRPC_ADDRESS")),
 				jsonrpc.WithTimeout(0),
 			},
@@ -57,6 +59,7 @@ func TestService(t *testing.T) {
 		{
 			name: "AddressInvalid",
 			parameters: []jsonrpc.Parameter{
+				jsonrpc.WithLogLevel(zerolog.Disabled),
 				jsonrpc.WithAddress(string([]byte{0x01})),
 				jsonrpc.WithTimeout(5 * time.Second),
 			},
diff --git a/types/address.go b/types/address.go
index 6a0332e..b7c9f5a 100644
--- a/types/address.go
+++ b/types/address.go
@@ -32,12 +32,12 @@ type Address [AddressLength]byte
 var zeroAddress = Address{}
 
 // IsZero returns true if the address is zero.
-func (a *Address) IsZero() bool {
+func (a Address) IsZero() bool {
 	return bytes.Equal(a[:], zeroAddress[:])
 }
 
 // String returns the string representation of the address.
-func (a *Address) String() string {
+func (a Address) String() string {
 	res := hex.EncodeToString(a[:])
 	// Leading 0s not allowed...
 	res = strings.TrimLeft(res, "0")
@@ -50,7 +50,7 @@ func (a *Address) String() string {
 }
 
 // Format formats the address.
-func (a *Address) Format(state fmt.State, v rune) {
+func (a Address) Format(state fmt.State, v rune) {
 	format := string(v)
 	switch v {
 	case 's':