diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9f54adff..a2b028f8 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: ['8.1', '8.2', '8.3']
+        php: ['8.1', '8.2', '8.3', '8.4']
         
     name: PHP ${{ matrix.php }} Test
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 7346a855..1ba0daea 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: [ '8.1', '8.2', '8.3' ]
+        php: [ '8.1', '8.2', '8.3', '8.4' ]
 
     name: PHP ${{ matrix.php }} Test
 
diff --git a/src/Account/Config.php b/src/Account/Config.php
index 63ed0b2c..51f5bd0c 100644
--- a/src/Account/Config.php
+++ b/src/Account/Config.php
@@ -19,9 +19,9 @@ class Config implements
     public function __construct(
         ?string $sms_callback_url = null,
         ?string $dr_callback_url = null,
-        int|string $max_outbound_request = null,
-        int|string $max_inbound_request = null,
-        int|string $max_calls_per_second = null
+        int|string|null $max_outbound_request = null,
+        int|string|null $max_inbound_request = null,
+        int|string|null $max_calls_per_second = null
     ) {
         if (!is_null($sms_callback_url)) {
             $this->data['sms_callback_url'] = $sms_callback_url;
diff --git a/src/Client.php b/src/Client.php
index aa866fb4..9a62ec28 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -231,7 +231,13 @@ public function __construct(
         // Disable throwing E_USER_DEPRECATED notices by default, the user can turn it on during development
         if (array_key_exists('show_deprecations', $this->options) && ($this->options['show_deprecations'] == true)) {
             set_error_handler(
-                static fn (int $errno, string $errstr, string $errfile = null, int $errline = null, array $errorcontext = null) => true,
+                static fn (
+                    int $errno,
+                    string $errstr,
+                    ?string $errfile = null,
+                    ?int $errline = null,
+                    ?array $errorcontext = null
+                ) => true,
                 E_USER_DEPRECATED
             );
         }
diff --git a/src/Client/Exception/Validation.php b/src/Client/Exception/Validation.php
index 27d4bb25..dc0d0648 100644
--- a/src/Client/Exception/Validation.php
+++ b/src/Client/Exception/Validation.php
@@ -11,7 +11,7 @@ class Validation extends Request
     public function __construct(
         string $message = '',
         int $code = 0,
-        Throwable $previous = null,
+        ?Throwable $previous = null,
         private readonly array $errors = []
     ) {
         parent::__construct($message, $code, $previous);
diff --git a/src/Conversation/Client.php b/src/Conversation/Client.php
index 1d9e53ca..07b012dc 100644
--- a/src/Conversation/Client.php
+++ b/src/Conversation/Client.php
@@ -30,8 +30,9 @@ public function getAPIResource(): APIResource
         return $this->api;
     }
 
-    public function listConversations(ListConversationFilter $conversationFilter = null): IterableAPICollection
-    {
+    public function listConversations(
+        ?ListConversationFilter $conversationFilter = null
+    ): IterableAPICollection {
         if (!$conversationFilter) {
             $conversationFilter = new ListConversationFilter();
         }
diff --git a/src/Meetings/Client.php b/src/Meetings/Client.php
index edbe729f..de4e20dd 100644
--- a/src/Meetings/Client.php
+++ b/src/Meetings/Client.php
@@ -90,7 +90,7 @@ public function updateRoom(string $id, array $payload): Room
         return $room;
     }
 
-    public function getAllListedRooms(string $start_id = null, string $end_id = null, int $size = 20): array
+    public function getAllListedRooms(?string $start_id = null, ?string $end_id = null, int $size = 20): array
     {
         $filterParams = [];
 
@@ -233,7 +233,7 @@ public function updateTheme(string $id, array $payload): ?ApplicationTheme
         return $applicationTheme;
     }
 
-    public function getRoomsByThemeId(string $themeId, string $startId = null, string $endId = null, int $size = 20): array
+    public function getRoomsByThemeId(string $themeId, ?string $startId = null, ?string $endId = null, int $size = 20): array
     {
         $this->api->setIsHAL(true);
         $this->api->setCollectionName('rooms');
diff --git a/src/Numbers/Client.php b/src/Numbers/Client.php
index 874648d0..d9d42a90 100644
--- a/src/Numbers/Client.php
+++ b/src/Numbers/Client.php
@@ -106,7 +106,7 @@ public function get(string $number): Number
      * @throws ClientException\Request
      * @throws ClientException\Server
      */
-    public function searchAvailable(string $country, FilterInterface $options = null): array
+    public function searchAvailable(string $country, ?FilterInterface $options = null): array
     {
         if (is_null($options)) {
             $options = new AvailableNumbers([
@@ -134,7 +134,7 @@ public function searchAvailable(string $country, FilterInterface $options = null
      * @throws ClientException\Request
      * @throws ClientException\Server
      */
-    public function searchOwned($number = null, FilterInterface $options = null): array
+    public function searchOwned($number = null, ?FilterInterface $options = null): array
     {
         if ($number !== null) {
             if ($options !== null) {
diff --git a/src/Subaccount/Client.php b/src/Subaccount/Client.php
index 03950a6c..965e5d2e 100644
--- a/src/Subaccount/Client.php
+++ b/src/Subaccount/Client.php
@@ -86,7 +86,7 @@ public function updateSubaccount(string $apiKey, string $subaccountApiKey, Accou
         return $this->api->partiallyUpdate($apiKey . '/subaccounts/' . $subaccountApiKey, $account->toArray());
     }
 
-    public function getCreditTransfers(string $apiKey, FilterInterface $filter = null): mixed
+    public function getCreditTransfers(string $apiKey, ?FilterInterface $filter = null): mixed
     {
         if (!$filter) {
             $filter = new EmptyFilter();
@@ -101,7 +101,7 @@ public function getCreditTransfers(string $apiKey, FilterInterface $filter = nul
         return array_map(fn ($item) => $hydrator->hydrate($item), $transfers);
     }
 
-    public function getBalanceTransfers(string $apiKey, FilterInterface $filter = null): mixed
+    public function getBalanceTransfers(string $apiKey, ?FilterInterface $filter = null): mixed
     {
         if (!$filter) {
             $filter = new EmptyFilter();
diff --git a/src/Users/Client.php b/src/Users/Client.php
index 46a16b9a..96e8c81f 100644
--- a/src/Users/Client.php
+++ b/src/Users/Client.php
@@ -29,7 +29,7 @@ public function getApiResource(): APIResource
         return $this->api;
     }
 
-    public function listUsers(FilterInterface $filter = null): IterableAPICollection
+    public function listUsers(?FilterInterface $filter = null): IterableAPICollection
     {
         if (is_null($filter)) {
             $filter = new EmptyFilter();
diff --git a/src/Verify/Client.php b/src/Verify/Client.php
index 6e3082c2..ef21d4ec 100644
--- a/src/Verify/Client.php
+++ b/src/Verify/Client.php
@@ -178,7 +178,7 @@ public function trigger($verification): Verification
      * @throws ClientException\Request
      * @throws ClientException\Server
      */
-    public function check(Verification|array|string $verification, string $code, string $ip = null): Verification
+    public function check(Verification|array|string $verification, string $code, ?string $ip = null): Verification
     {
         if (is_array($verification)) {
             trigger_error(
diff --git a/src/Verify/RequestPSD2.php b/src/Verify/RequestPSD2.php
index d395560b..33aaf930 100644
--- a/src/Verify/RequestPSD2.php
+++ b/src/Verify/RequestPSD2.php
@@ -39,7 +39,7 @@ public function __construct(
         protected string $number,
         protected string $payee,
         protected string $amount,
-        int $workflowId = null
+        ?int $workflowId = null
     ) {
         if ($workflowId) {
             $this->setWorkflowId($workflowId);
diff --git a/src/Verify2/Client.php b/src/Verify2/Client.php
index 7826b273..a1c50805 100644
--- a/src/Verify2/Client.php
+++ b/src/Verify2/Client.php
@@ -82,7 +82,7 @@ public static function isSilentAuthRequest(BaseVerifyRequest $request): bool
         return false;
     }
 
-    public function listCustomTemplates(TemplateFilter $filter = null): IterableAPICollection
+    public function listCustomTemplates(?TemplateFilter $filter = null): IterableAPICollection
     {
         $collection = $this->api->search($filter, '/templates');
         $collection->setNaiveCount(true);
@@ -158,7 +158,7 @@ public function deleteCustomTemplateFragment(string $templateId, string $fragmen
         return true;
     }
 
-    public function listTemplateFragments(string $templateId, TemplateFilter $filter = null): IterableAPICollection
+    public function listTemplateFragments(string $templateId, ?TemplateFilter $filter = null): IterableAPICollection
     {
         $api = clone $this->getAPIResource();
         $api->setCollectionName('template_fragments');
diff --git a/src/Voice/Client.php b/src/Voice/Client.php
index c50bf1e4..c16272ce 100644
--- a/src/Voice/Client.php
+++ b/src/Voice/Client.php
@@ -182,7 +182,7 @@ public function playTTS(string $callId, Talk $action): array
         return $this->api->update($callId . '/talk', $payload);
     }
 
-    public function search(FilterInterface $filter = null): IterableAPICollection
+    public function search(?FilterInterface $filter = null): IterableAPICollection
     {
         $response = $this->api->search($filter);
         $response->setApiResource(clone $this->api);
diff --git a/test/ProactiveConnect/ClientTest.php b/test/ProactiveConnect/ClientTest.php
index 8811b4ba..c62c129c 100644
--- a/test/ProactiveConnect/ClientTest.php
+++ b/test/ProactiveConnect/ClientTest.php
@@ -570,7 +570,7 @@ public function testWillDownloadItemCsv(): void
         fwrite($handle, (string) $response->getContents());
         fseek($handle, 0);
 
-        while (($row = fgetcsv($handle)) !== false) {
+        while (($row = fgetcsv($handle, 0, ',', '"', '\\')) !== false) {
             if (!$header) {
                 $header = $row;
             } else {