diff --git a/Handler/FirePHPHandler.php b/Handler/FirePHPHandler.php
index 3627f50..8713f6c 100644
--- a/Handler/FirePHPHandler.php
+++ b/Handler/FirePHPHandler.php
@@ -37,7 +37,7 @@ public function onKernelResponse(ResponseEvent $event)
         }
 
         $request = $event->getRequest();
-        if (!preg_match('{\bFirePHP/\d+\.\d+\b}', $request->headers->get('User-Agent'))
+        if (!preg_match('{\bFirePHP/\d+\.\d+\b}', $request->headers->get('User-Agent', ''))
             && !$request->headers->has('X-FirePHP-Version')) {
             self::$sendHeaders = false;
             $this->headers = [];
diff --git a/LICENSE b/LICENSE
index 0083704..0138f8f 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2004-2023 Fabien Potencier
+Copyright (c) 2004-present Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/Tests/Formatter/ConsoleFormatterTest.php b/Tests/Formatter/ConsoleFormatterTest.php
index 8e847c5..bf754f4 100644
--- a/Tests/Formatter/ConsoleFormatterTest.php
+++ b/Tests/Formatter/ConsoleFormatterTest.php
@@ -28,7 +28,7 @@ public function testFormat(array|LogRecord $record, $expectedMessage)
         self::assertSame($expectedMessage, $formatter->format($record));
     }
 
-    public function providerFormatTests(): array
+    public static function providerFormatTests(): array
     {
         $currentDateTime = new \DateTimeImmutable();
 
diff --git a/Tests/Handler/ConsoleHandlerTest.php b/Tests/Handler/ConsoleHandlerTest.php
index f7f09c3..b2f8a79 100644
--- a/Tests/Handler/ConsoleHandlerTest.php
+++ b/Tests/Handler/ConsoleHandlerTest.php
@@ -65,7 +65,7 @@ public function testVerbosityMapping($verbosity, $level, $isHandling, array $map
         $levelName = Logger::getLevelName($level);
         $levelName = sprintf('%-9s', $levelName);
 
-        $realOutput = $this->getMockBuilder(Output::class)->setMethods(['doWrite'])->getMock();
+        $realOutput = $this->getMockBuilder(Output::class)->onlyMethods(['doWrite'])->getMock();
         $realOutput->setVerbosity($verbosity);
         if ($realOutput->isDebug()) {
             $log = "16:21:54 $levelName [app] My info message\n";
@@ -82,7 +82,7 @@ public function testVerbosityMapping($verbosity, $level, $isHandling, array $map
         $this->assertFalse($handler->handle($infoRecord), 'The handler finished handling the log.');
     }
 
-    public function provideVerbosityMappingTests()
+    public static function provideVerbosityMappingTests()
     {
         return [
             [OutputInterface::VERBOSITY_QUIET, Logger::ERROR, true],
diff --git a/Tests/Handler/FingersCrossed/HttpCodeActivationStrategyTest.php b/Tests/Handler/FingersCrossed/HttpCodeActivationStrategyTest.php
index a5c877b..37286d3 100644
--- a/Tests/Handler/FingersCrossed/HttpCodeActivationStrategyTest.php
+++ b/Tests/Handler/FingersCrossed/HttpCodeActivationStrategyTest.php
@@ -56,7 +56,7 @@ public function testIsActivated($url, $record, $expected)
         self::assertEquals($expected, $strategy->isHandlerActivated($record));
     }
 
-    public function isActivatedProvider(): array
+    public static function isActivatedProvider(): array
     {
         return [
             ['/test',  RecordFactory::create(Logger::ERROR), true],
@@ -72,7 +72,7 @@ public function isActivatedProvider(): array
         ];
     }
 
-    private function getContextException(int $code): array
+    private static function getContextException(int $code): array
     {
         return ['exception' => new HttpException($code)];
     }
diff --git a/Tests/Handler/FingersCrossed/NotFoundActivationStrategyTest.php b/Tests/Handler/FingersCrossed/NotFoundActivationStrategyTest.php
index 220cbe5..36c448c 100644
--- a/Tests/Handler/FingersCrossed/NotFoundActivationStrategyTest.php
+++ b/Tests/Handler/FingersCrossed/NotFoundActivationStrategyTest.php
@@ -36,7 +36,7 @@ public function testIsActivated(string $url, array|LogRecord $record, bool $expe
         self::assertEquals($expected, $strategy->isHandlerActivated($record));
     }
 
-    public function isActivatedProvider(): array
+    public static function isActivatedProvider(): array
     {
         return [
             ['/test',      RecordFactory::create(Logger::DEBUG), false],
diff --git a/Tests/Handler/FirePHPHandlerTest.php b/Tests/Handler/FirePHPHandlerTest.php
index 70d1915..3a47eb5 100644
--- a/Tests/Handler/FirePHPHandlerTest.php
+++ b/Tests/Handler/FirePHPHandlerTest.php
@@ -112,6 +112,22 @@ private function createHandler(): FirePHPHandler
         return $handler;
     }
 
+    public function testOnKernelResponseShouldNotTriggerDeprecation()
+    {
+        $handler = $this->createHandler();
+
+        $request = Request::create('/');
+        $request->headers->remove('User-Agent');
+
+        $error = null;
+        set_error_handler(function ($type, $message) use (&$error) { $error = $message; }, \E_DEPRECATED);
+
+        $this->dispatchResponseEvent($handler, $request);
+        restore_error_handler();
+
+        $this->assertNull($error);
+    }
+
     private function dispatchResponseEvent(FirePHPHandler $handler, Request $request): Response
     {
         $dispatcher = new EventDispatcher();