diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bb21ad1..e712290 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['8.1', '8.2', '8.3', '8.4']
+        php: ['8.1', '8.2', '8.3', '8.4', '8.5']
 
     steps:
       - name: Checkout
diff --git a/packages/logtide/src/Integration/ErrorListenerIntegration.php b/packages/logtide/src/Integration/ErrorListenerIntegration.php
index 179f5d9..dd9541f 100644
--- a/packages/logtide/src/Integration/ErrorListenerIntegration.php
+++ b/packages/logtide/src/Integration/ErrorListenerIntegration.php
@@ -62,10 +62,13 @@ public function teardown(): void
 
     private static function severityToLevel(int $severity): LogLevel
     {
+        // E_STRICT is intentionally absent: the level was removed in PHP 8.0 and
+        // the constant itself is deprecated since 8.4, so referencing it here
+        // would emit a deprecation from inside the error handler.
         return match (true) {
             (bool) ($severity & (E_ERROR | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR)) => LogLevel::CRITICAL,
             (bool) ($severity & (E_WARNING | E_CORE_WARNING | E_COMPILE_WARNING | E_USER_WARNING | E_RECOVERABLE_ERROR)) => LogLevel::WARN,
-            (bool) ($severity & (E_NOTICE | E_USER_NOTICE | E_STRICT | E_DEPRECATED | E_USER_DEPRECATED)) => LogLevel::INFO,
+            (bool) ($severity & (E_NOTICE | E_USER_NOTICE | E_DEPRECATED | E_USER_DEPRECATED)) => LogLevel::INFO,
             default => LogLevel::ERROR,
         };
     }
diff --git a/packages/logtide/src/Serializer/ErrorSerializer.php b/packages/logtide/src/Serializer/ErrorSerializer.php
index 017df33..a9a9ed4 100644
--- a/packages/logtide/src/Serializer/ErrorSerializer.php
+++ b/packages/logtide/src/Serializer/ErrorSerializer.php
@@ -65,11 +65,13 @@ public static function serializePhpError(int $severity, string $message, string
 
     private static function errorLevelToString(int $level): string
     {
+        // E_STRICT is intentionally absent: the level was removed in PHP 8.0 and
+        // the constant itself is deprecated since 8.4, so referencing it here
+        // would emit a deprecation from inside the error handler.
         return match ($level) {
             E_ERROR, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR => 'E_ERROR',
             E_WARNING, E_CORE_WARNING, E_COMPILE_WARNING, E_USER_WARNING => 'E_WARNING',
             E_NOTICE, E_USER_NOTICE => 'E_NOTICE',
-            E_STRICT => 'E_STRICT',
             E_DEPRECATED, E_USER_DEPRECATED => 'E_DEPRECATED',
             E_RECOVERABLE_ERROR => 'E_RECOVERABLE_ERROR',
             default => 'E_UNKNOWN',
diff --git a/packages/logtide/tests/Unit/Serializer/ErrorSerializerTest.php b/packages/logtide/tests/Unit/Serializer/ErrorSerializerTest.php
index c709b37..fa6d88b 100644
--- a/packages/logtide/tests/Unit/Serializer/ErrorSerializerTest.php
+++ b/packages/logtide/tests/Unit/Serializer/ErrorSerializerTest.php
@@ -82,6 +82,8 @@ public function testErrorLevelMapping(): void
         $this->assertSame('E_WARNING', ErrorSerializer::serializePhpError(E_WARNING, '', '', 0)['type']);
         $this->assertSame('E_NOTICE', ErrorSerializer::serializePhpError(E_NOTICE, '', '', 0)['type']);
         $this->assertSame('E_DEPRECATED', ErrorSerializer::serializePhpError(E_DEPRECATED, '', '', 0)['type']);
-        $this->assertSame('E_STRICT', ErrorSerializer::serializePhpError(E_STRICT, '', '', 0)['type']);
+        $this->assertSame('E_DEPRECATED', ErrorSerializer::serializePhpError(E_USER_DEPRECATED, '', '', 0)['type']);
+        $this->assertSame('E_RECOVERABLE_ERROR', ErrorSerializer::serializePhpError(E_RECOVERABLE_ERROR, '', '', 0)['type']);
+        $this->assertSame('E_UNKNOWN', ErrorSerializer::serializePhpError(0, '', '', 0)['type']);
     }
 }
diff --git a/packages/logtide/tests/Unit/State/ScopeTest.php b/packages/logtide/tests/Unit/State/ScopeTest.php
index 7d91191..477b8de 100644
--- a/packages/logtide/tests/Unit/State/ScopeTest.php
+++ b/packages/logtide/tests/Unit/State/ScopeTest.php
@@ -18,7 +18,6 @@ final class ScopeTest extends TestCase
     protected function tearDown(): void
     {
         $ref = new \ReflectionProperty(Scope::class, 'globalEventProcessors');
-        $ref->setAccessible(true);
         $ref->setValue(null, []);
     }
 
diff --git a/phpunit.xml b/phpunit.xml
index 98d4626..2d9cefd 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -5,6 +5,7 @@
          colors="true"
          failOnRisky="true"
          failOnWarning="true"
+         failOnDeprecation="true"
          displayDetailsOnTestsThatTriggerDeprecations="true">
     <testsuites>
         <testsuite name="Core">