diff --git a/src/ApiClient.php b/src/ApiClient.php
index 66210f5..7d0a3ff 100755
--- a/src/ApiClient.php
+++ b/src/ApiClient.php
@@ -57,7 +57,7 @@ class ApiClient implements ApiInterface
      * @param TokenStorageInterface|null $tokenStorage
      * @throws ApiClientException
      */
-    public function __construct(string $userId, string $secret, TokenStorageInterface $tokenStorage = null)
+    public function __construct(string $userId, string $secret, ?TokenStorageInterface $tokenStorage = null)
     {
         if ($tokenStorage === null) {
             $tokenStorage = new FileStorage();
@@ -307,7 +307,7 @@ public function removeAddressBook(int $id): ?array
      * @deprecated
      * @see ApiClient::get()
      */
-    public function listAddressBooks(int $limit = null, int $offset = null): ?array
+    public function listAddressBooks(?int $limit = null, ?int $offset = null): ?array
     {
         $data = array();
         if (null !== $limit) {
@@ -380,7 +380,7 @@ public function updateEmailVariables(int $bookID, string $email, array $vars): ?
      * @deprecated
      * @see ApiClient::get()
      */
-    public function getEmailsFromBook(int $id, int $limit = null, int $offset = null): ?array
+    public function getEmailsFromBook(int $id, ?int $limit = null, ?int $offset = null): ?array
     {
         $data = [];
         if (null !== $limit) {
@@ -477,7 +477,7 @@ public function campaignCost(int $bookID): ?array
      * @deprecated
      * @see ApiClient::get()
      */
-    public function listCampaigns(int $limit = null, int $offset = null): ?array
+    public function listCampaigns(?int $limit = null, ?int $offset = null): ?array
     {
         $data = [];
         if (!empty($limit)) {
@@ -563,7 +563,7 @@ public function createCampaign(
         string $type = '',
         bool   $useTemplateId = false,
         string $sendDate = '',
-        int    $segmentId = null,
+        ?int   $segmentId = null,
         array  $attachmentsBinary = []
     ): ?array
     {
@@ -884,7 +884,7 @@ public function smtpGetEmailInfoById($id): ?array
      * @deprecated
      * @see ApiClient::get()
      */
-    public function smtpListUnsubscribed(int $limit = null, int $offset = null): ?array
+    public function smtpListUnsubscribed(?int $limit = null, ?int $offset = null): ?array
     {
         $data = array();
         if (null !== $limit) {
@@ -974,7 +974,7 @@ public function smtpSendMail(array $email): ?array
      * @deprecated
      * @see ApiClient::get()
      */
-    public function pushListCampaigns(int $limit = null, int $offset = null): ?array
+    public function pushListCampaigns(?int $limit = null, ?int $offset = null): ?array
     {
         $data = [];
         if (null !== $limit) {
@@ -997,7 +997,7 @@ public function pushListCampaigns(int $limit = null, int $offset = null): ?array
      * @deprecated
      * @see ApiClient::get()
      */
-    public function pushListWebsites(int $limit = null, int $offset = null): ?array
+    public function pushListWebsites(?int $limit = null, ?int $offset = null): ?array
     {
         $data = array();
         if (null !== $limit) {
@@ -1048,7 +1048,7 @@ public function pushListWebsiteVariables(int $websiteId): ?array
      * @deprecated
      * @see ApiClient::get()
      */
-    public function pushListWebsiteSubscriptions(int $websiteID, int $limit = null, int $offset = null): ?array
+    public function pushListWebsiteSubscriptions(int $websiteID, ?int $limit = null, ?int $offset = null): ?array
     {
         $data = [];
         if (null !== $limit) {
diff --git a/src/ApiClientException.php b/src/ApiClientException.php
index 1ddbcaf..ef42257 100755
--- a/src/ApiClientException.php
+++ b/src/ApiClientException.php
@@ -32,12 +32,12 @@ class ApiClientException extends Exception
      * @param string|null $curlErrors
      */
     public function __construct(
-        string    $message = "",
-        int       $code = 0,
-        Throwable $previous = null,
-        array     $responseBody = [],
-        string    $headers = null,
-        string    $curlErrors = null
+        string     $message = "",
+        int        $code = 0,
+        ?Throwable $previous = null,
+        array      $responseBody = [],
+        ?string    $headers = null,
+        ?string    $curlErrors = null
     )
     {
         $this->response = $responseBody;