diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f1102d63d..bb51e01f2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,15 +27,15 @@ jobs:
           - ubuntu-latest
           - windows-latest
         php:
-          - { version: '7.2', phpunit: '^8.5.40' }
-          - { version: '7.3', phpunit: '^9.6.21' }
-          - { version: '7.4', phpunit: '^9.6.21' }
-          - { version: '8.0', phpunit: '^9.6.21' }
-          - { version: '8.1', phpunit: '^9.6.21' }
-          - { version: '8.2', phpunit: '^9.6.21' }
-          - { version: '8.3', phpunit: '^9.6.21' }
-          - { version: '8.4', phpunit: '^9.6.21' }
-          - { version: '8.5', phpunit: '^9.6.25' }
+          - { version: '7.2', phpunit: '^8.5.52' }
+          - { version: '7.3', phpunit: '^9.6.34' }
+          - { version: '7.4', phpunit: '^9.6.34' }
+          - { version: '8.0', phpunit: '^9.6.34' }
+          - { version: '8.1', phpunit: '^9.6.34' }
+          - { version: '8.2', phpunit: '^9.6.34' }
+          - { version: '8.3', phpunit: '^9.6.34' }
+          - { version: '8.4', phpunit: '^9.6.34' }
+          - { version: '8.5', phpunit: '^9.6.34' }
         dependencies:
           - lowest
           - highest
diff --git a/composer.json b/composer.json
index 607891141..c00da9591 100644
--- a/composer.json
+++ b/composer.json
@@ -38,7 +38,7 @@
         "monolog/monolog": "^1.6|^2.0|^3.0",
         "phpbench/phpbench": "^1.0",
         "phpstan/phpstan": "^1.3",
-        "phpunit/phpunit": "^8.5|^9.6",
+        "phpunit/phpunit": "^8.5.52|^9.6.33",
         "vimeo/psalm": "^4.17"
     },
     "suggest": {
diff --git a/src/HttpClient/HttpClient.php b/src/HttpClient/HttpClient.php
index 2a373d930..fc0823373 100644
--- a/src/HttpClient/HttpClient.php
+++ b/src/HttpClient/HttpClient.php
@@ -57,7 +57,7 @@ public function sendRequest(Request $request, Options $options): Response
         }
 
         $responseHeaders = [];
-        $responseHeaderCallback = function ($curlHandle, $headerLine) use (&$responseHeaders): int {
+        $responseHeaderCallback = static function ($curlHandle, $headerLine) use (&$responseHeaders): int {
             return Http::parseResponseHeaders($headerLine, $responseHeaders);
         };
 
diff --git a/src/Logs/LogsAggregator.php b/src/Logs/LogsAggregator.php
index e2fb5ea78..8d1ab7db4 100644
--- a/src/Logs/LogsAggregator.php
+++ b/src/Logs/LogsAggregator.php
@@ -83,7 +83,7 @@ public function add(
             $log->setAttribute('sentry.sdk.version', $client->getSdkVersion());
         }
 
-        $hub->configureScope(function (Scope $scope) use ($log) {
+        $hub->configureScope(static function (Scope $scope) use ($log) {
             $user = $scope->getUser();
             if ($user !== null) {
                 if ($user->getId() !== null) {
@@ -186,7 +186,7 @@ private function getTraceId(HubInterface $hub): string
 
         $traceId = '';
 
-        $hub->configureScope(function (Scope $scope) use (&$traceId) {
+        $hub->configureScope(static function (Scope $scope) use (&$traceId) {
             $traceId = (string) $scope->getPropagationContext()->getTraceId();
         });
 
diff --git a/src/Metrics/Metrics.php b/src/Metrics/Metrics.php
index 936538e19..a45d7e6fc 100644
--- a/src/Metrics/Metrics.php
+++ b/src/Metrics/Metrics.php
@@ -109,7 +109,7 @@ public function timing(
         int $stackLevel = 0
     ) {
         return trace(
-            function () use ($callback) {
+            static function () use ($callback) {
                 return $callback();
             },
             SpanContext::make()
diff --git a/src/Metrics/MetricsAggregator.php b/src/Metrics/MetricsAggregator.php
index e18ca7ddf..a25df0b35 100644
--- a/src/Metrics/MetricsAggregator.php
+++ b/src/Metrics/MetricsAggregator.php
@@ -79,7 +79,7 @@ public function add(
             ];
 
             if ($options->shouldSendDefaultPii()) {
-                $hub->configureScope(function (Scope $scope) use (&$defaultAttributes) {
+                $hub->configureScope(static function (Scope $scope) use (&$defaultAttributes) {
                     $user = $scope->getUser();
                     if ($user !== null) {
                         if ($user->getId() !== null) {
@@ -111,7 +111,7 @@ public function add(
             $spanId = $span->getSpanId();
             $traceId = $span->getTraceId();
         } else {
-            $hub->configureScope(function (Scope $scope) use (&$traceId, &$spanId) {
+            $hub->configureScope(static function (Scope $scope) use (&$traceId, &$spanId) {
                 $propagationContext = $scope->getPropagationContext();
                 $traceId = $propagationContext->getTraceId();
                 $spanId = $propagationContext->getSpanId();
diff --git a/src/State/HubAdapter.php b/src/State/HubAdapter.php
index 503153860..8e4343858 100644
--- a/src/State/HubAdapter.php
+++ b/src/State/HubAdapter.php
@@ -206,7 +206,7 @@ public function __clone()
     /**
      * @see https://www.php.net/manual/en/language.oop5.magic.php#object.wakeup
      */
-    public function __wakeup()
+    public function __unserialize(array $data)
     {
         throw new \BadMethodCallException('Unserializing instances of this class is forbidden.');
     }
@@ -214,7 +214,7 @@ public function __wakeup()
     /**
      * @see https://www.php.net/manual/en/language.oop5.magic.php#object.sleep
      */
-    public function __sleep()
+    public function __serialize()
     {
         throw new \BadMethodCallException('Serializing instances of this class is forbidden.');
     }
diff --git a/src/Tracing/Span.php b/src/Tracing/Span.php
index 09fe62a20..f45050620 100644
--- a/src/Tracing/Span.php
+++ b/src/Tracing/Span.php
@@ -300,7 +300,7 @@ public function setStatus(?SpanStatus $status)
      */
     public function setHttpStatus(int $statusCode)
     {
-        SentrySdk::getCurrentHub()->configureScope(function (Scope $scope) use ($statusCode) {
+        SentrySdk::getCurrentHub()->configureScope(static function (Scope $scope) use ($statusCode) {
             $scope->setContext('response', [
                 'status_code' => $statusCode,
             ]);
diff --git a/src/functions.php b/src/functions.php
index 36c7c8b50..a7412fce7 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -252,7 +252,7 @@ function startTransaction(TransactionContext $context, array $customSamplingCont
  */
 function trace(callable $trace, SpanContext $context)
 {
-    return SentrySdk::getCurrentHub()->withScope(function (Scope $scope) use ($context, $trace) {
+    return SentrySdk::getCurrentHub()->withScope(static function (Scope $scope) use ($context, $trace) {
         $parentSpan = $scope->getSpan();
 
         // If there is a span set on the scope and it's sampled there is an active transaction.
@@ -299,7 +299,7 @@ function getTraceparent(): string
     }
 
     $traceParent = '';
-    $hub->configureScope(function (Scope $scope) use (&$traceParent) {
+    $hub->configureScope(static function (Scope $scope) use (&$traceParent) {
         $traceParent = $scope->getPropagationContext()->toTraceparent();
     });
 
@@ -342,7 +342,7 @@ function getBaggage(): string
     }
 
     $baggage = '';
-    $hub->configureScope(function (Scope $scope) use (&$baggage) {
+    $hub->configureScope(static function (Scope $scope) use (&$baggage) {
         $baggage = $scope->getPropagationContext()->toBaggage();
     });
 
@@ -358,7 +358,7 @@ function getBaggage(): string
 function continueTrace(string $sentryTrace, string $baggage): TransactionContext
 {
     $hub = SentrySdk::getCurrentHub();
-    $hub->configureScope(function (Scope $scope) use ($sentryTrace, $baggage) {
+    $hub->configureScope(static function (Scope $scope) use ($sentryTrace, $baggage) {
         $propagationContext = PropagationContext::fromHeaders($sentryTrace, $baggage);
         $scope->setPropagationContext($propagationContext);
     });
@@ -393,7 +393,7 @@ function trace_metrics(): TraceMetrics
  */
 function addFeatureFlag(string $name, bool $result): void
 {
-    SentrySdk::getCurrentHub()->configureScope(function (Scope $scope) use ($name, $result) {
+    SentrySdk::getCurrentHub()->configureScope(static function (Scope $scope) use ($name, $result) {
         $scope->addFeatureFlag($name, $result);
     });
 }
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index a6cf67c8b..fb8b51d61 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -1033,7 +1033,7 @@ public function testAttachStacktrace(): void
         $transport = $this->createMock(TransportInterface::class);
         $transport->expects($this->once())
                   ->method('send')
-                  ->with($this->callback(function (Event $event): bool {
+                  ->with($this->callback(static function (Event $event): bool {
                       $result = $event->getStacktrace();
 
                       return $result !== null;
diff --git a/tests/FrameBuilderTest.php b/tests/FrameBuilderTest.php
index 667b85a18..ecb01f0e1 100644
--- a/tests/FrameBuilderTest.php
+++ b/tests/FrameBuilderTest.php
@@ -290,7 +290,7 @@ public function testGetFunctionArgumentsWithVariadicParameters(): void
         $options = new Options([]);
         $frameBuilder = new FrameBuilder($options, new RepresentationSerializer($options));
 
-        $testFunction = function (string $first, int $second, ...$rest) {
+        $testFunction = static function (string $first, int $second, ...$rest) {
         };
 
         $backtraceFrame = [
@@ -325,7 +325,7 @@ public function testGetFunctionArgumentsWithOnlyVariadicParameters(): void
         $options = new Options([]);
         $frameBuilder = new FrameBuilder($options, new RepresentationSerializer($options));
 
-        $testFunction = function (...$args) {
+        $testFunction = static function (...$args) {
         };
 
         $backtraceFrame = [
@@ -352,7 +352,7 @@ public function testGetFunctionArgumentsWithEmptyVariadicParameters(): void
         $options = new Options([]);
         $frameBuilder = new FrameBuilder($options, new RepresentationSerializer($options));
 
-        $testFunction = function (string $first, ...$rest) {
+        $testFunction = static function (string $first, ...$rest) {
         };
 
         $backtraceFrame = [
@@ -381,7 +381,7 @@ public function testGetFunctionArgumentsWithNullValues(): void
         $options = new Options([]);
         $frameBuilder = new FrameBuilder($options, new RepresentationSerializer($options));
 
-        $testFunction = function (string $first, $second, ...$rest) {
+        $testFunction = static function (string $first, $second, ...$rest) {
         };
 
         $backtraceFrame = [
@@ -411,7 +411,7 @@ public function testGetFunctionArgumentsWithGapsInBacktraceArrayIndices(): void
         $options = new Options([]);
         $frameBuilder = new FrameBuilder($options, new RepresentationSerializer($options));
 
-        $testFunction = function (string $first, int $second, ...$rest) {
+        $testFunction = static function (string $first, int $second, ...$rest) {
         };
 
         $backtraceFrameArgs = [];
diff --git a/tests/FunctionsTest.php b/tests/FunctionsTest.php
index 949f9fadd..07e0bd918 100644
--- a/tests/FunctionsTest.php
+++ b/tests/FunctionsTest.php
@@ -224,15 +224,15 @@ public function testWithMonitor(): void
         $hub->expects($this->exactly(2))
             ->method('captureCheckIn')
             ->with(
-                $this->callback(function (string $slug): bool {
+                $this->callback(static function (string $slug): bool {
                     return $slug === 'test-crontab';
                 }),
-                $this->callback(function (CheckInStatus $checkInStatus): bool {
+                $this->callback(static function (CheckInStatus $checkInStatus): bool {
                     // just check for type CheckInStatus
                     return true;
                 }),
                 $this->anything(),
-                $this->callback(function (MonitorConfig $monitorConfig): bool {
+                $this->callback(static function (MonitorConfig $monitorConfig): bool {
                     return $monitorConfig->getSchedule()->getValue() === '*/5 * * * *'
                         && $monitorConfig->getSchedule()->getType() === MonitorSchedule::TYPE_CRONTAB
                         && $monitorConfig->getCheckinMargin() === 5
@@ -243,7 +243,7 @@ public function testWithMonitor(): void
 
         SentrySdk::setCurrentHub($hub);
 
-        withMonitor('test-crontab', function () {
+        withMonitor('test-crontab', static function () {
             // Do something...
         }, new MonitorConfig(
             new MonitorSchedule(MonitorSchedule::TYPE_CRONTAB, '*/5 * * * *'),
@@ -261,15 +261,15 @@ public function testWithMonitorCallableThrows(): void
         $hub->expects($this->exactly(2))
             ->method('captureCheckIn')
             ->with(
-                $this->callback(function (string $slug): bool {
+                $this->callback(static function (string $slug): bool {
                     return $slug === 'test-crontab';
                 }),
-                $this->callback(function (CheckInStatus $checkInStatus): bool {
+                $this->callback(static function (CheckInStatus $checkInStatus): bool {
                     // just check for type CheckInStatus
                     return true;
                 }),
                 $this->anything(),
-                $this->callback(function (MonitorConfig $monitorConfig): bool {
+                $this->callback(static function (MonitorConfig $monitorConfig): bool {
                     return $monitorConfig->getSchedule()->getValue() === '*/5 * * * *'
                         && $monitorConfig->getSchedule()->getType() === MonitorSchedule::TYPE_CRONTAB
                         && $monitorConfig->getCheckinMargin() === 5
@@ -280,7 +280,7 @@ public function testWithMonitorCallableThrows(): void
 
         SentrySdk::setCurrentHub($hub);
 
-        withMonitor('test-crontab', function () {
+        withMonitor('test-crontab', static function () {
             throw new \Exception();
         }, new MonitorConfig(
             new MonitorSchedule(MonitorSchedule::TYPE_CRONTAB, '*/5 * * * *'),
@@ -352,7 +352,7 @@ public function testTraceReturnsClosureResult(): void
     {
         $returnValue = 'foo';
 
-        $result = trace(function () use ($returnValue) {
+        $result = trace(static function () use ($returnValue) {
             return $returnValue;
         }, new SpanContext());
 
@@ -379,7 +379,7 @@ public function testTraceCorrectlyReplacesAndRestoresCurrentSpan(): void
         $this->assertSame($transaction, $hub->getSpan());
 
         try {
-            trace(function () {
+            trace(static function () {
                 throw new \RuntimeException('Throwing should still restore the previous span');
             }, new SpanContext());
         } catch (\RuntimeException $e) {
diff --git a/tests/Logs/LogsAggregatorTest.php b/tests/Logs/LogsAggregatorTest.php
index 83a91e1da..89e175a70 100644
--- a/tests/Logs/LogsAggregatorTest.php
+++ b/tests/Logs/LogsAggregatorTest.php
@@ -170,7 +170,7 @@ public function testAttributesAreAddedToLogMessage(): void
         $hub = new Hub($client);
         SentrySdk::setCurrentHub($hub);
 
-        $hub->configureScope(function (Scope $scope) {
+        $hub->configureScope(static function (Scope $scope) {
             $userDataBag = new UserDataBag();
             $userDataBag->setId('unique_id');
             $userDataBag->setEmail('foo@example.com');
diff --git a/tests/Logs/LogsTest.php b/tests/Logs/LogsTest.php
index 3aab97419..4dd361b56 100644
--- a/tests/Logs/LogsTest.php
+++ b/tests/Logs/LogsTest.php
@@ -171,7 +171,7 @@ private function assertEvent(callable $assert, array $options = []): ClientInter
         $transport = $this->createMock(TransportInterface::class);
         $transport->expects($this->once())
                   ->method('send')
-                  ->with($this->callback(function (Event $event) use ($assert): bool {
+                  ->with($this->callback(static function (Event $event) use ($assert): bool {
                       $assert($event);
 
                       return true;
diff --git a/tests/Serializer/AbstractSerializerTest.php b/tests/Serializer/AbstractSerializerTest.php
index 36f753c73..89932ba1a 100644
--- a/tests/Serializer/AbstractSerializerTest.php
+++ b/tests/Serializer/AbstractSerializerTest.php
@@ -458,7 +458,7 @@ public function serializableCallableProvider(): array
 
         return [
             [
-                'callable' => function (array $param1) {
+                'callable' => static function (array $param1) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -466,7 +466,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [array param1]',
             ],
             [
-                'callable' => function ($param1a) {
+                'callable' => static function ($param1a) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -474,7 +474,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [mixed|null param1a]',
             ],
             [
-                'callable' => function (callable $param1c) {
+                'callable' => static function (callable $param1c) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -482,7 +482,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [callable param1c]',
             ],
             [
-                'callable' => function (\stdClass $param1d) {
+                'callable' => static function (\stdClass $param1d) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -490,7 +490,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [stdClass param1d]',
             ],
             [
-                'callable' => function (?\stdClass $param1e = null) {
+                'callable' => static function (?\stdClass $param1e = null) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -498,7 +498,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [stdClass|null [param1e]]',
             ],
             [
-                'callable' => function (array &$param1f) {
+                'callable' => static function (array &$param1f) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -506,7 +506,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [array &param1f]',
             ],
             [
-                'callable' => function (?array &$param1g = null) {
+                'callable' => static function (?array &$param1g = null) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -534,7 +534,7 @@ public function serializableCallableProvider(): array
                 'expected' => 'Callable void ' . SerializerTestObject::class . '::testy []',
             ],
             [
-                'callable' => function (int $param1_70a) {
+                'callable' => static function (int $param1_70a) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -542,7 +542,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [int param1_70a]',
             ],
             [
-                'callable' => function (&$param): int {
+                'callable' => static function (&$param): int {
                     return (int) $param;
                 },
                 'expected' => $prettyClosureNames
@@ -550,7 +550,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda int ' . __NAMESPACE__ . '\\{closure} [mixed|null &param]',
             ],
             [
-                'callable' => function (int $param): ?int {
+                'callable' => static function (int $param): ?int {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -558,7 +558,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda int ' . __NAMESPACE__ . '\\{closure} [int param]',
             ],
             [
-                'callable' => function (?int $param1_70b) {
+                'callable' => static function (?int $param1_70b) {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
@@ -566,7 +566,7 @@ public function serializableCallableProvider(): array
                     : 'Lambda ' . __NAMESPACE__ . '\\{closure} [int|null param1_70b]',
             ],
             [
-                'callable' => function (?int $param1_70c): void {
+                'callable' => static function (?int $param1_70c): void {
                     throw new \Exception('Don\'t even think about invoke me');
                 },
                 'expected' => $prettyClosureNames
diff --git a/tests/State/HubTest.php b/tests/State/HubTest.php
index bb735cb96..0fb31e2cd 100644
--- a/tests/State/HubTest.php
+++ b/tests/State/HubTest.php
@@ -240,7 +240,7 @@ public function testCaptureMessage(array $functionCallArgs, array $expectedFunct
         $eventId = EventId::generate();
         $hub = new Hub();
 
-        $hub->configureScope(function (Scope $scope) use ($propagationContext): void {
+        $hub->configureScope(static function (Scope $scope) use ($propagationContext): void {
             $scope->setPropagationContext($propagationContext);
         });
 
@@ -299,7 +299,7 @@ public function testCaptureException(array $functionCallArgs, array $expectedFun
         $eventId = EventId::generate();
         $hub = new Hub();
 
-        $hub->configureScope(function (Scope $scope) use ($propagationContext): void {
+        $hub->configureScope(static function (Scope $scope) use ($propagationContext): void {
             $scope->setPropagationContext($propagationContext);
         });
 
@@ -354,7 +354,7 @@ public function testCaptureLastError(array $functionCallArgs, array $expectedFun
         $eventId = EventId::generate();
         $hub = new Hub();
 
-        $hub->configureScope(function (Scope $scope) use ($propagationContext): void {
+        $hub->configureScope(static function (Scope $scope) use ($propagationContext): void {
             $scope->setPropagationContext($propagationContext);
         });
 
@@ -813,7 +813,7 @@ public function testStartTransactionUpdatesTheDscSampleRate(): void
         $client->expects($this->once())
             ->method('getOptions')
             ->willReturn(new Options([
-                'traces_sampler' => function (SamplingContext $samplingContext): float {
+                'traces_sampler' => static function (SamplingContext $samplingContext): float {
                     return 1.0;
                 },
             ]));
diff --git a/tests/State/ScopeTest.php b/tests/State/ScopeTest.php
index 281cbadb9..f2d99db01 100644
--- a/tests/State/ScopeTest.php
+++ b/tests/State/ScopeTest.php
@@ -405,7 +405,7 @@ public function testAddEventProcessor(): void
             return null;
         });
 
-        $scope->addEventProcessor(function () use (&$callback3Called) {
+        $scope->addEventProcessor(static function () use (&$callback3Called) {
             $callback3Called = true;
 
             return null;
@@ -425,7 +425,7 @@ public function testEventProcessorReceivesTheEventAndEventHint(): void
         $processorCalled = false;
         $processorReceivedHint = null;
 
-        $scope->addEventProcessor(function (Event $eventArg, EventHint $hint) use (&$processorCalled, &$processorReceivedHint): ?Event {
+        $scope->addEventProcessor(static function (Event $eventArg, EventHint $hint) use (&$processorCalled, &$processorReceivedHint): ?Event {
             $processorCalled = true;
             $processorReceivedHint = $hint;
 
diff --git a/tests/Transport/HttpTransportTest.php b/tests/Transport/HttpTransportTest.php
index 1d34137ae..206261eb0 100644
--- a/tests/Transport/HttpTransportTest.php
+++ b/tests/Transport/HttpTransportTest.php
@@ -62,7 +62,7 @@ public function testSend(Response $response, ResultStatus $expectedResultStatus,
             $this->logger->expects($this->exactly(\count($messages)))
                 ->method($level)
                 ->with($this->logicalOr(
-                    ...array_map(function (string $message) {
+                    ...array_map(static function (string $message) {
                         return new StringMatchesFormatDescription($message);
                     }, $messages)
                 ));