diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
new file mode 100644
index 0000000..cd3d475
--- /dev/null
+++ b/.github/workflows/tests.yml
@@ -0,0 +1,44 @@
+name: PHPUnit
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php: [ '7.4', '8.0', '8.1', '8.2', '8.3', '8.4', '8.5' ]
+
+    name: PHP ${{ matrix.php }}
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: xdebug
+
+      - name: Install dependencies
+        run: composer install --no-interaction --prefer-dist --no-progress
+
+      - name: Run PHPUnit
+        run: vendor/bin/phpunit --coverage-text=coverage.txt
+
+      - name: Check coverage
+        run: |
+          cat coverage.txt
+          COVERAGE=$(grep -A3 'Summary:' coverage.txt | grep 'Lines:' | grep -oP '\d+\.\d+(?=%)')
+          THRESHOLD=100
+          if (( $(echo "$COVERAGE < $THRESHOLD" | bc -l) )); then
+            echo "Coverage is $COVERAGE%, below ${THRESHOLD}% threshold"
+            exit 1
+          fi
+          echo "Coverage is $COVERAGE% (threshold: ${THRESHOLD}%)"
diff --git a/composer.json b/composer.json
index 6ac775d..8b9f87e 100644
--- a/composer.json
+++ b/composer.json
@@ -8,7 +8,7 @@
     "packaged/helpers": "~1.0||~2.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "~4.5"
+    "phpunit/phpunit": "~9"
   },
   "autoload": {
     "psr-4": {
diff --git a/phpunit.xml.dist b/phpunit.xml
similarity index 62%
rename from phpunit.xml.dist
rename to phpunit.xml
index 55fd283..8958c0a 100755
--- a/phpunit.xml.dist
+++ b/phpunit.xml
@@ -1,27 +1,23 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<phpunit backupGlobals="false"
-         backupStaticAttributes="false"
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+         backupGlobals="false"
          colors="true"
+         processIsolation="false"
+         stopOnFailure="true"
          convertErrorsToExceptions="true"
          convertNoticesToExceptions="true"
          convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="true"
-         syntaxCheck="true"
          bootstrap="vendor/autoload.php">
   <testsuites>
     <testsuite name="Fortifi Test Suite">
       <directory>./tests</directory>
     </testsuite>
   </testsuites>
-  <filter>
-    <whitelist>
+  <coverage>
+    <include>
       <directory suffix=".php">src</directory>
-    </whitelist>
-    <blacklist>
-      <directory suffix=".php">vendor</directory>
-      <directory suffix=".php">tests</directory>
-    </blacklist>
-  </filter>
+    </include>
+  </coverage>
 </phpunit>
diff --git a/src/Payloads/FortifiWebhookPayload.php b/src/Payloads/FortifiWebhookPayload.php
index 140a365..f1e1601 100644
--- a/src/Payloads/FortifiWebhookPayload.php
+++ b/src/Payloads/FortifiWebhookPayload.php
@@ -29,6 +29,7 @@ final public function __construct($event)
    * @return mixed data which can be serialized by <b>json_encode</b>,
    *       which is a value of any type other than a resource.
    */
+  #[\ReturnTypeWillChange]
   public function jsonSerialize()
   {
     return [
diff --git a/src/Webhooks.php b/src/Webhooks.php
index ff99e23..86202f4 100644
--- a/src/Webhooks.php
+++ b/src/Webhooks.php
@@ -62,7 +62,7 @@ public static function getPayload($json)
     $decoded = json_decode($json);
     $events = static::all();
     $event = Objects::property($decoded, 'event');
-    if(isset($events[$event]))
+    if($event !== null && isset($events[$event]))
     {
       return call_user_func([$events[$event], 'hydrateFromJson'], $json);
     }
diff --git a/tests/Payloads/FortifiWebhookPayloadTest.php b/tests/Payloads/FortifiWebhookPayloadTest.php
index ad1d75c..0ba71ae 100644
--- a/tests/Payloads/FortifiWebhookPayloadTest.php
+++ b/tests/Payloads/FortifiWebhookPayloadTest.php
@@ -2,8 +2,10 @@
 namespace Fortifi\Tests\Webhooks\Payloads;
 
 use Fortifi\Webhooks\Payloads\FortifiWebhookPayload;
+use Fortifi\Webhooks\Payloads\Test\TestWHP;
+use PHPUnit\Framework\TestCase;
 
-class FortifiWebhookPayloadTest extends \PHPUnit_Framework_TestCase
+class FortifiWebhookPayloadTest extends TestCase
 {
   public function testWebookPayload()
   {
@@ -25,4 +27,35 @@ public function testWebookPayload()
       $this->assertEquals(456, $object->getRequestId());
     }
   }
+
+  /**
+   * Test that jsonSerialize works without deprecation in PHP 8+
+   * Requires #[\ReturnTypeWillChange] attribute on jsonSerialize()
+   */
+  public function testJsonSerializeCompatibility()
+  {
+    $deprecation = null;
+    set_error_handler(
+      function($errno, $errstr) use (&$deprecation) {
+        if(strpos($errstr, 'jsonSerialize') !== false)
+        {
+          $deprecation = $errstr;
+        }
+        return true;
+      },
+      E_DEPRECATED
+    );
+
+    try
+    {
+      $payload = new TestWHP('test.event');
+      json_encode($payload);
+    }
+    finally
+    {
+      restore_error_handler();
+    }
+
+    $this->assertNull($deprecation, $deprecation ?? '');
+  }
 }
diff --git a/tests/Payloads/Test/TestWHPTest.php b/tests/Payloads/Test/TestWHPTest.php
index f81c442..51e97ac 100644
--- a/tests/Payloads/Test/TestWHPTest.php
+++ b/tests/Payloads/Test/TestWHPTest.php
@@ -2,8 +2,9 @@
 namespace Fortifi\Tests\Webhooks\Payloads\Test;
 
 use Fortifi\Webhooks\Payloads\Test\TestWHP;
+use PHPUnit\Framework\TestCase;
 
-class TestWHPTest extends \PHPUnit_Framework_TestCase
+class TestWHPTest extends TestCase
 {
   public function testTransport()
   {
diff --git a/tests/WebhooksTest.php b/tests/WebhooksTest.php
new file mode 100644
index 0000000..e337635
--- /dev/null
+++ b/tests/WebhooksTest.php
@@ -0,0 +1,103 @@
+<?php
+namespace Fortifi\Tests\Webhooks;
+
+use Fortifi\Webhooks\Events\CustomerWHE;
+use Fortifi\Webhooks\Events\InvoiceWHE;
+use Fortifi\Webhooks\Payloads\Customer\CustomerCreatedWHP;
+use Fortifi\Webhooks\Payloads\Invoice\InvoiceWHP;
+use Fortifi\Webhooks\Webhooks;
+use PHPUnit\Framework\TestCase;
+
+class WebhooksTest extends TestCase
+{
+  public function testAll()
+  {
+    $all = Webhooks::all();
+
+    $this->assertIsArray($all);
+    $this->assertNotEmpty($all);
+    $this->assertArrayHasKey(CustomerWHE::CREATED, $all);
+    $this->assertEquals(CustomerCreatedWHP::class, $all[CustomerWHE::CREATED]);
+  }
+
+  public function testGetPayloadWithValidEvent()
+  {
+    $json = json_encode([
+      'event' => CustomerWHE::CREATED,
+      'sig'   => 'test-sig',
+      'uuid'  => 'test-uuid',
+      'rqid'  => 'test-rqid',
+      'data'  => ['customerFid' => 'cust-123'],
+    ]);
+
+    $payload = Webhooks::getPayload($json);
+
+    $this->assertInstanceOf(CustomerCreatedWHP::class, $payload);
+    $this->assertEquals(CustomerWHE::CREATED, $payload->getEventType());
+    $this->assertEquals('test-uuid', $payload->getPayloadId());
+    $this->assertEquals('test-rqid', $payload->getRequestId());
+  }
+
+  public function testGetPayloadWithUnknownEvent()
+  {
+    $json = json_encode([
+      'event' => 'unknown.event',
+      'sig'   => 'test-sig',
+      'uuid'  => 'test-uuid',
+      'rqid'  => 'test-rqid',
+      'data'  => [],
+    ]);
+
+    $payload = Webhooks::getPayload($json);
+
+    $this->assertNull($payload);
+  }
+
+  public function testGetPayloadWithMissingEvent()
+  {
+    $json = json_encode([
+      'sig'  => 'test-sig',
+      'uuid' => 'test-uuid',
+      'data' => [],
+    ]);
+
+    $payload = Webhooks::getPayload($json);
+
+    $this->assertNull($payload);
+  }
+
+  public function testAllWithDisplayNames()
+  {
+    $displayNames = Webhooks::allWithDisplayNames();
+
+    $this->assertIsArray($displayNames);
+    $this->assertNotEmpty($displayNames);
+    $this->assertCount(count(Webhooks::all()), $displayNames);
+
+    foreach($displayNames as $name)
+    {
+      $this->assertIsString($name);
+      $this->assertNotEmpty($name);
+    }
+  }
+
+  public function testGetDisplayName()
+  {
+    $this->assertEquals('Customer Created', Webhooks::getDisplayName('customer.created'));
+    $this->assertEquals('Customer Email Unsubscribed', Webhooks::getDisplayName('customer.email.unsubscribed'));
+    $this->assertEquals('Invoice Add Payment', Webhooks::getDisplayName('invoice.add.payment'));
+  }
+
+  public function testGetDisplayNamePreservesCase()
+  {
+    $this->assertEquals('Test Event', Webhooks::getDisplayName('test.event'));
+  }
+
+  public function testAllEventsMapToValidClasses()
+  {
+    foreach(Webhooks::all() as $event => $class)
+    {
+      $this->assertTrue(class_exists($class), "Class $class for event $event does not exist");
+    }
+  }
+}