diff --git a/composer.json b/composer.json
index 69eb742..581f67f 100644
--- a/composer.json
+++ b/composer.json
@@ -14,9 +14,9 @@
     },
     "require-dev" : {
         "friendsofphp/php-cs-fixer": "^3.66",
-        "phpstan/phpstan": "^1.12",
-        "phpstan/phpstan-phpunit": "^1.4",
-        "phpstan/phpstan-strict-rules": "^1.6",
+        "phpstan/phpstan": "^2.1",
+        "phpstan/phpstan-phpunit": "^2.0",
+        "phpstan/phpstan-strict-rules": "^2.0",
         "phpstan/extension-installer": "^1.4",
         "phpunit/phpunit" : "^9.6"
     },
diff --git a/lib/Message.php b/lib/Message.php
index ff8139f..9f36086 100644
--- a/lib/Message.php
+++ b/lib/Message.php
@@ -82,11 +82,8 @@ public function getBodyAsString(): string
 
             return ob_get_clean();
         }
-        /**
-         * @var string|int|null $contentLength
-         */
         $contentLength = $this->getHeader('Content-Length');
-        if (null !== $contentLength && (is_int($contentLength) || ctype_digit($contentLength))) {
+        if (null !== $contentLength && ctype_digit($contentLength)) {
             return stream_get_contents($body, (int) $contentLength);
         }
 
diff --git a/lib/Sapi.php b/lib/Sapi.php
index 4383fda..e2c4b1a 100644
--- a/lib/Sapi.php
+++ b/lib/Sapi.php
@@ -86,7 +86,7 @@ public static function sendResponse(ResponseInterface $response): void
         $contentLength = $response->getHeader('Content-Length');
         if (null !== $contentLength) {
             $output = fopen('php://output', 'wb');
-            if (is_resource($body) && 'stream' == get_resource_type($body)) {
+            if (is_resource($body) && 'stream' === get_resource_type($body)) {
                 // a workaround to make PHP more possible to use mmap based copy, see https://github.com/sabre-io/http/pull/119
                 $left = (int) $contentLength;
                 // copy with 4MiB chunks
diff --git a/phpstan.neon b/phpstan.neon
index 509ce6a..024b14d 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,6 +1,5 @@
 parameters:
   level: 6
-  phpVersion: 70430 # PHP 7.4.30
   ignoreErrors:
   -
     message: "#^Negated boolean expression is always true.$#"
@@ -12,12 +11,8 @@ parameters:
     path: lib/Client.php
   -
     message: "#^Left side of || is always false.$#"
-    count: 6
+    count: 19
     path: lib/Client.php
-  -
-    message: "#^Else branch is unreachable because ternary operator condition is always true.$#"
-    count: 1
-    path: lib/Auth/Digest.php
   -
     message: "#^Strict comparison using !== between '' and non-empty-string will always evaluate to true.$#"
     count: 1
diff --git a/tests/HTTP/Auth/AWSTest.php b/tests/HTTP/Auth/AWSTest.php
index 2f1c1a9..88b18c6 100644
--- a/tests/HTTP/Auth/AWSTest.php
+++ b/tests/HTTP/Auth/AWSTest.php
@@ -200,7 +200,7 @@ public function test401(): void
     {
         $this->auth->requireLogin();
         $test = preg_match('/^AWS$/', $this->response->getHeader('WWW-Authenticate'), $matches);
-        self::assertTrue(true == $test, 'The WWW-Authenticate response didn\'t match our pattern');
+        self::assertTrue(1 === $test, 'The WWW-Authenticate response didn\'t match our pattern');
     }
 
     /**
diff --git a/tests/HTTP/Auth/DigestTest.php b/tests/HTTP/Auth/DigestTest.php
index 78d5933..f5bc609 100644
--- a/tests/HTTP/Auth/DigestTest.php
+++ b/tests/HTTP/Auth/DigestTest.php
@@ -166,7 +166,7 @@ private function getServerTokens(int $qop = Digest::QOP_AUTH): array
         $test = preg_match('/Digest realm="'.self::REALM.'",qop="'.$qopstr.'",nonce="([0-9a-f]*)",opaque="([0-9a-f]*)"/',
             $this->response->getHeader('WWW-Authenticate'), $matches);
 
-        self::assertTrue(true == $test, 'The WWW-Authenticate response didn\'t match our pattern. We received: '.$this->response->getHeader('WWW-Authenticate'));
+        self::assertTrue(1 === $test, 'The WWW-Authenticate response didn\'t match our pattern. We received: '.$this->response->getHeader('WWW-Authenticate'));
 
         $nonce = $matches[1];
         $opaque = $matches[2];
diff --git a/tests/HTTP/ClientTest.php b/tests/HTTP/ClientTest.php
index 97345e2..d13ed1f 100644
--- a/tests/HTTP/ClientTest.php
+++ b/tests/HTTP/ClientTest.php
@@ -537,7 +537,7 @@ public function doRequest(RequestInterface $request): ResponseInterface
         // If nothing modified $response, we're using the default behavior.
         if (is_null($response)) {
             return parent::doRequest($request);
-        } else { /* @phpstan-ignore-line phpstan thinks Else branch is unreachable */
+        } else {
             return $response;
         }
     }
@@ -557,7 +557,7 @@ protected function curlStuff($curlHandle): array
         // If nothing modified $return, we're using the default behavior.
         if (is_null($return)) {
             return parent::curlStuff($curlHandle);
-        } else { /* @phpstan-ignore-line phpstan thinks Else branch is unreachable */
+        } else {
             return $return;
         }
     }
@@ -577,7 +577,7 @@ protected function curlExec($curlHandle): string
         // If nothing modified $return, we're using the default behavior.
         if (is_null($return)) {
             return parent::curlExec($curlHandle);
-        } else { /* @phpstan-ignore-line phpstan thinks Else branch is unreachable */
+        } else {
             return $return;
         }
     }
diff --git a/tests/HTTP/RequestTest.php b/tests/HTTP/RequestTest.php
index 86322b3..848c286 100644
--- a/tests/HTTP/RequestTest.php
+++ b/tests/HTTP/RequestTest.php
@@ -35,7 +35,7 @@ public function testGetQueryParametersNoData(): void
     }
 
     /**
-     * @backupGlobals
+     * @backupGlobals enabled
      */
     public function testCreateFromPHPRequest(): void
     {