diff --git a/src/Casts/MoneyCast.php b/src/Casts/MoneyCast.php
index 7838d7e..76f79d7 100644
--- a/src/Casts/MoneyCast.php
+++ b/src/Casts/MoneyCast.php
@@ -27,7 +27,7 @@ abstract class MoneyCast implements CastsAttributes
      *
      * @param  mixed  $forceDecimals
      */
-    public function __construct(string $currency = null, $forceDecimals = null)
+    public function __construct(?string $currency = null, $forceDecimals = null)
     {
         $this->currency = $currency;
         $this->forceDecimals = is_string($forceDecimals)
diff --git a/src/Formatters/CurrencySymbolMoneyFormatter.php b/src/Formatters/CurrencySymbolMoneyFormatter.php
index f0a086a..ad19937 100644
--- a/src/Formatters/CurrencySymbolMoneyFormatter.php
+++ b/src/Formatters/CurrencySymbolMoneyFormatter.php
@@ -31,7 +31,7 @@ class CurrencySymbolMoneyFormatter implements MoneyFormatter
      * @param  bool  $right
      * @param  string|null  $locale
      */
-    public function __construct($right = false, $locale = null, Currencies $currencies = null)
+    public function __construct($right = false, $locale = null, ?Currencies $currencies = null)
     {
         $this->right = $right;
         $this->locale = $locale ?: Money::getLocale();
diff --git a/src/Money.php b/src/Money.php
index 810bd0b..10470a5 100644
--- a/src/Money.php
+++ b/src/Money.php
@@ -7,7 +7,6 @@
 use Illuminate\Contracts\Support\Jsonable;
 use Illuminate\Support\Traits\Macroable;
 use JsonSerializable;
-use ReflectionMethod;
 
 /**
  * Money.
@@ -41,16 +40,16 @@ class Money implements Arrayable, Jsonable, JsonSerializable
 {
     use CurrenciesTrait;
     use LocaleTrait;
+    use Macroable {
+        Macroable::__call as macroCall;
+        Macroable::__callStatic as macroCallStatic;
+    }
     use MoneyFactory {
         MoneyFactory::__callStatic as factoryCallStatic;
     }
     use MoneyFormatterTrait;
-    use MoneySerializerTrait;
     use MoneyParserTrait;
-    use Macroable {
-        Macroable::__call as macroCall;
-        Macroable::__callStatic as macroCallStatic;
-    }
+    use MoneySerializerTrait;
 
     /**
      * @var \Money\Money
@@ -281,41 +280,4 @@ private static function convertResult($result)
 
         return $results;
     }
-
-    /**
-     * Resolve calculator.
-     *
-     * @return \Money\Calculator
-     *
-     * @throws \RuntimeException
-     */
-    private static function resolveCalculator()
-    {
-        $reflection = new ReflectionMethod(\Money\Money::class, 'getCalculator');
-
-        if ($reflection->isPublic()) {
-            $calculator = call_user_func([\Money\Money::class, 'getCalculator']);
-
-            return new $calculator();
-        }
-
-        $calculators = [
-            \Money\Calculator\BcMathCalculator::class,
-            \Money\Calculator\GmpCalculator::class,
-            \Money\Calculator\PhpCalculator::class,
-        ];
-
-        foreach ($calculators as $calculator) {
-            if (! class_exists($calculator)) {
-                continue;
-            }
-
-            /** @var Calculator $calculator */
-            if ($calculator::supported()) {
-                return new $calculator();
-            }
-        }
-
-        throw new \RuntimeException('Cannot find calculator for money calculations');
-    }
 }
diff --git a/src/MoneyFormatterTrait.php b/src/MoneyFormatterTrait.php
index 1f09f95..19c6d16 100644
--- a/src/MoneyFormatterTrait.php
+++ b/src/MoneyFormatterTrait.php
@@ -25,7 +25,7 @@ trait MoneyFormatterTrait
      *
      * @throws \InvalidArgumentException
      */
-    public function format($locale = null, Currencies $currencies = null, $style = NumberFormatter::CURRENCY)
+    public function format($locale = null, ?Currencies $currencies = null, $style = NumberFormatter::CURRENCY)
     {
         $defaultFormatter = config('money.defaultFormatter');
 
@@ -69,7 +69,7 @@ public function formatByAggregate(array $formatters)
      * @param  int  $fractionDigits
      * @return string
      */
-    public function formatByBitcoin($fractionDigits = 2, Currencies $currencies = null)
+    public function formatByBitcoin($fractionDigits = 2, ?Currencies $currencies = null)
     {
         $formatter = new BitcoinMoneyFormatter($fractionDigits, $currencies ?: new BitcoinCurrencies());
 
@@ -81,10 +81,9 @@ public function formatByBitcoin($fractionDigits = 2, Currencies $currencies = nu
      *
      * @param  bool  $right
      * @param  string|null  $locale
-     * @param  \Money\Currencies  $currencies
      * @return string
      */
-    public function formatByCurrencySymbol($right = false, $locale = null, Currencies $currencies = null)
+    public function formatByCurrencySymbol($right = false, $locale = null, ?Currencies $currencies = null)
     {
         $formatter = new CurrencySymbolMoneyFormatter($right, $locale ?: static::getLocale(), $currencies ?: static::getCurrencies());
 
@@ -96,7 +95,7 @@ public function formatByCurrencySymbol($right = false, $locale = null, Currencie
      *
      * @return string
      */
-    public function formatByDecimal(Currencies $currencies = null)
+    public function formatByDecimal(?Currencies $currencies = null)
     {
         $formatter = new DecimalMoneyFormatter($currencies ?: static::getCurrencies());
 
@@ -110,7 +109,7 @@ public function formatByDecimal(Currencies $currencies = null)
      * @param  int  $style
      * @return string
      */
-    public function formatByIntl($locale = null, Currencies $currencies = null, $style = NumberFormatter::CURRENCY)
+    public function formatByIntl($locale = null, ?Currencies $currencies = null, $style = NumberFormatter::CURRENCY)
     {
         $numberFormatter = new NumberFormatter($locale ?: static::getLocale(), $style);
         $formatter = new IntlMoneyFormatter($numberFormatter, $currencies ?: static::getCurrencies());
@@ -127,7 +126,7 @@ public function formatByIntl($locale = null, Currencies $currencies = null, $sty
      */
     public function formatByIntlLocalizedDecimal(
         $locale = null,
-        Currencies $currencies = null,
+        ?Currencies $currencies = null,
         $style = NumberFormatter::CURRENCY
     ) {
         $numberFormatter = new NumberFormatter($locale ?: static::getLocale(), $style);
diff --git a/src/MoneyParserTrait.php b/src/MoneyParserTrait.php
index d1f6fee..4bf8e80 100644
--- a/src/MoneyParserTrait.php
+++ b/src/MoneyParserTrait.php
@@ -156,7 +156,7 @@ public static function parseByBitcoin(
     public static function parseByDecimal(
         $money,
         $fallbackCurrency = null,
-        Currencies $currencies = null,
+        ?Currencies $currencies = null,
         $convert = true
     ) {
         $parser = new DecimalMoneyParser($currencies ?: static::getCurrencies());
@@ -178,7 +178,7 @@ public static function parseByIntl(
         $money,
         $fallbackCurrency = null,
         $locale = null,
-        Currencies $currencies = null,
+        ?Currencies $currencies = null,
         $style = null,
         $convert = true
     ) {
@@ -206,7 +206,7 @@ public static function parseByIntlLocalizedDecimal(
         $money,
         $fallbackCurrency = null,
         $locale = null,
-        Currencies $currencies = null,
+        ?Currencies $currencies = null,
         $style = null,
         $convert = true
     ) {
diff --git a/src/MoneySerializerTrait.php b/src/MoneySerializerTrait.php
index ced876f..cbb22ef 100644
--- a/src/MoneySerializerTrait.php
+++ b/src/MoneySerializerTrait.php
@@ -57,7 +57,6 @@ public function serializeByArray()
     /**
      * Serialize by serializer.
      *
-     * @param  \Cknow\Money\MoneySerializer  $serializer
      * @return mixed
      */
     public function serializeBySerializer(MoneySerializer $serializer)
diff --git a/src/helpers.php b/src/helpers.php
index 7bf3b3d..de7d557 100644
--- a/src/helpers.php
+++ b/src/helpers.php
@@ -151,14 +151,13 @@ function money_parse_by_bitcoin(
      *
      * @param  string  $money
      * @param  \Money\Currency|string|null  $fallbackCurrency
-     * @param  \Money\Currencies|null  $currencies
      * @param  bool  $convert
      * @return \Cknow\Money\Money|\Money\Money
      */
     function money_parse_by_decimal(
         $money,
         $fallbackCurrency = null,
-        Money\Currencies $currencies = null,
+        ?Money\Currencies $currencies = null,
         $convert = true
     ) {
         return Cknow\Money\Money::parseByDecimal(
@@ -177,7 +176,6 @@ function money_parse_by_decimal(
      * @param  string  $money
      * @param  \Money\Currency|string|null  $fallbackCurrency
      * @param  string|null  $locale
-     * @param  \Money\Currencies|null  $currencies
      * @param  int|null  $style
      * @param  bool  $convert
      * @return \Cknow\Money\Money|\Money\Money
@@ -186,7 +184,7 @@ function money_parse_by_intl(
         $money,
         $fallbackCurrency = null,
         $locale = null,
-        Money\Currencies $currencies = null,
+        ?Money\Currencies $currencies = null,
         $style = null,
         $convert = true
     ) {
@@ -208,7 +206,6 @@ function money_parse_by_intl(
      * @param  string  $money
      * @param  \Money\Currency|string|null  $fallbackCurrency
      * @param  string|null  $locale
-     * @param  \Money\Currencies|null  $currencies
      * @param  int|null  $style
      * @param  bool  $convert
      * @return \Cknow\Money\Money|\Money\Money
@@ -217,7 +214,7 @@ function money_parse_by_intl_localized_decimal(
         $money,
         $fallbackCurrency = null,
         $locale = null,
-        Money\Currencies $currencies = null,
+        ?Money\Currencies $currencies = null,
         $style = null,
         $convert = true
     ) {
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 0512238..22b9d56 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -11,7 +11,6 @@ abstract class TestCase extends AbstractPackageTestCase
      * Setup the application environment.
      *
      * @param  \Illuminate\Contracts\Foundation\Application  $app
-     * @return void
      */
     protected function getEnvironmentSetUp($app): void
     {
@@ -22,8 +21,6 @@ protected function getEnvironmentSetUp($app): void
 
     /**
      * Get the service provider class.
-     *
-     * @return string
      */
     protected static function getServiceProviderClass(): string
     {