diff --git a/src/Connection/ConnectionLimitingPool.php b/src/Connection/ConnectionLimitingPool.php
index 68adc65c..b51fd749 100644
--- a/src/Connection/ConnectionLimitingPool.php
+++ b/src/Connection/ConnectionLimitingPool.php
@@ -42,8 +42,6 @@ private static function formatUri(Request $request): string
         return $scheme . '://' . $authority;
     }
 
-    private int $connectionLimit;
-
     private ConnectionFactory $connectionFactory;
 
     /** @var array<string, \ArrayObject<int, Future<Connection>>> */
@@ -67,14 +65,13 @@ private static function formatUri(Request $request): string
 
     private int $openConnectionCount = 0;
 
-    private function __construct(int $connectionLimit, ?ConnectionFactory $connectionFactory = null)
+    private function __construct(private readonly int $connectionLimit, ?ConnectionFactory $connectionFactory = null)
     {
         if ($connectionLimit < 1) {
             throw new \Error('The connection limit must be greater than 0');
         }
 
-        $this->connectionLimit = $connectionLimit;
-        $this->connectionFactory = $connectionFactory ?? new DefaultConnectionFactory;
+        $this->connectionFactory = $connectionFactory ?? new DefaultConnectionFactory();
     }
 
     public function __clone()
diff --git a/src/Connection/DefaultConnectionFactory.php b/src/Connection/DefaultConnectionFactory.php
index 0b342786..7ba029c7 100644
--- a/src/Connection/DefaultConnectionFactory.php
+++ b/src/Connection/DefaultConnectionFactory.php
@@ -18,14 +18,13 @@
 
 final class DefaultConnectionFactory implements ConnectionFactory
 {
-    private ?Socket\SocketConnector $connector;
+    private readonly ConnectContext $connectContext;
 
-    private ?ConnectContext $connectContext;
-
-    public function __construct(?Socket\SocketConnector $connector = null, ?ConnectContext $connectContext = null)
-    {
-        $this->connector = $connector;
-        $this->connectContext = $connectContext;
+    public function __construct(
+        private readonly ?Socket\SocketConnector $connector = null,
+        ?ConnectContext $connectContext = null,
+    ) {
+        $this->connectContext = $connectContext ?? new ConnectContext();
     }
 
     public function create(Request $request, Cancellation $cancellation): Connection
@@ -33,7 +32,7 @@ public function create(Request $request, Cancellation $cancellation): Connection
         $connectStart = now();
 
         $connector = $this->connector ?? Socket\socketConnector();
-        $connectContext = $this->connectContext ?? new ConnectContext;
+        $connectContext = $this->connectContext;
 
         $uri = $request->getUri();
         $scheme = $uri->getScheme();
diff --git a/src/Connection/Http1Connection.php b/src/Connection/Http1Connection.php
index e798d4df..44440ffe 100644
--- a/src/Connection/Http1Connection.php
+++ b/src/Connection/Http1Connection.php
@@ -69,8 +69,6 @@ final class Http1Connection implements Connection
     /** @var list<\Closure():void>|null */
     private ?array $onClose = [];
 
-    private float $timeoutGracePeriod;
-
     private float $lastUsedAt;
 
     private bool $explicitTimeout = false;
@@ -87,13 +85,12 @@ public function __construct(
         Socket $socket,
         private readonly float $connectDuration,
         private readonly ?float $tlsHandshakeDuration,
-        float $timeoutGracePeriod = 2
+        private readonly float $timeoutGracePeriod = 2,
     ) {
         $this->socket = $socket;
         $this->localAddress = $socket->getLocalAddress();
         $this->remoteAddress = $socket->getRemoteAddress();
         $this->tlsInfo = $socket->getTlsInfo();
-        $this->timeoutGracePeriod = $timeoutGracePeriod;
         $this->lastUsedAt = now();
         $this->watchIdleConnection();
     }
diff --git a/src/Connection/HttpStream.php b/src/Connection/HttpStream.php
index 387596f9..4371e550 100644
--- a/src/Connection/HttpStream.php
+++ b/src/Connection/HttpStream.php
@@ -12,66 +12,73 @@
 use Amp\Socket\TlsInfo;
 use function Amp\Http\Client\processRequest;
 
+/**
+ * @psalm-type RequestCallbackType = callable(Request, Cancellation, HttpStream):Response
+ * @psalm-type ReleaseCallbackType = callable():void
+ */
 final class HttpStream implements Stream
 {
     use ForbidSerialization;
     use ForbidCloning;
 
+    /**
+     * @param RequestCallbackType $RequestCallbackType
+     * @param ReleaseCallbackType $ReleaseCallbackType
+     */
     public static function fromConnection(
         Connection $connection,
-        callable $requestCallback,
-        callable $releaseCallback
+        callable $RequestCallbackType,
+        callable $ReleaseCallbackType
     ): self {
         return new self(
             $connection->getLocalAddress(),
             $connection->getRemoteAddress(),
             $connection->getTlsInfo(),
-            $requestCallback,
-            $releaseCallback
+            $RequestCallbackType,
+            $ReleaseCallbackType,
         );
     }
 
-    public static function fromStream(Stream $stream, callable $requestCallback, callable $releaseCallback): self
+    /**
+     * @param RequestCallbackType $RequestCallbackType
+     * @param ReleaseCallbackType $ReleaseCallbackType
+     */
+    public static function fromStream(Stream $stream, callable $RequestCallbackType, callable $ReleaseCallbackType): self
     {
         return new self(
             $stream->getLocalAddress(),
             $stream->getRemoteAddress(),
             $stream->getTlsInfo(),
-            $requestCallback,
-            $releaseCallback
+            $RequestCallbackType,
+            $ReleaseCallbackType,
         );
     }
 
-    private SocketAddress $localAddress;
-
-    private SocketAddress $remoteAddress;
-
-    private ?TlsInfo $tlsInfo;
-
     /** @var callable */
-    private $requestCallback;
+    private $RequestCallbackType;
 
     /** @var callable|null */
-    private $releaseCallback;
+    private $ReleaseCallbackType;
 
+    /**
+     * @param RequestCallbackType $RequestCallbackType
+     * @param ReleaseCallbackType $ReleaseCallbackType
+     */
     private function __construct(
-        SocketAddress $localAddress,
-        SocketAddress $remoteAddress,
-        ?TlsInfo $tlsInfo,
-        callable $requestCallback,
-        callable $releaseCallback
+        private readonly SocketAddress $localAddress,
+        private readonly SocketAddress $remoteAddress,
+        private readonly ?TlsInfo $tlsInfo,
+        callable $RequestCallbackType,
+        callable $ReleaseCallbackType,
     ) {
-        $this->localAddress = $localAddress;
-        $this->remoteAddress = $remoteAddress;
-        $this->tlsInfo = $tlsInfo;
-        $this->requestCallback = $requestCallback;
-        $this->releaseCallback = $releaseCallback;
+        $this->RequestCallbackType = $RequestCallbackType;
+        $this->ReleaseCallbackType = $ReleaseCallbackType;
     }
 
     public function __destruct()
     {
-        if ($this->releaseCallback !== null) {
-            ($this->releaseCallback)();
+        if ($this->ReleaseCallbackType !== null) {
+            ($this->ReleaseCallbackType)();
         }
     }
 
@@ -80,13 +87,13 @@ public function __destruct()
      */
     public function request(Request $request, Cancellation $cancellation): Response
     {
-        if ($this->releaseCallback === null) {
+        if ($this->ReleaseCallbackType === null) {
             throw new \Error('A stream may only be used for a single request');
         }
 
-        $this->releaseCallback = null;
+        $this->ReleaseCallbackType = null;
 
-        return processRequest($request, [], fn (): Response => ($this->requestCallback)($request, $cancellation, $this));
+        return processRequest($request, [], fn (): Response => ($this->RequestCallbackType)($request, $cancellation, $this));
     }
 
     public function getLocalAddress(): SocketAddress
diff --git a/src/Connection/InterceptedStream.php b/src/Connection/InterceptedStream.php
index cee6f045..1b40cfdf 100644
--- a/src/Connection/InterceptedStream.php
+++ b/src/Connection/InterceptedStream.php
@@ -21,13 +21,10 @@ final class InterceptedStream implements Stream
 
     private static \WeakMap $requestInterceptors;
 
-    private Stream $stream;
-
     private ?NetworkInterceptor $interceptor;
 
-    public function __construct(Stream $stream, NetworkInterceptor $interceptor)
+    public function __construct(private readonly Stream $stream, NetworkInterceptor $interceptor)
     {
-        $this->stream = $stream;
         $this->interceptor = $interceptor;
     }
 
@@ -37,14 +34,14 @@ public function __construct(Stream $stream, NetworkInterceptor $interceptor)
     public function request(Request $request, Cancellation $cancellation): Response
     {
         return processRequest($request, [], function () use ($request, $cancellation): Response {
-            if (!$this->interceptor) {
+            $interceptor = $this->interceptor;
+            $this->interceptor = null;
+
+            if (!$interceptor) {
                 throw new \Error(__METHOD__ . ' may only be invoked once per instance. '
                     . 'If you need to implement retries or otherwise issue multiple requests, register an ApplicationInterceptor to do so.');
             }
 
-            $interceptor = $this->interceptor;
-            $this->interceptor = null;
-
             /** @psalm-suppress RedundantPropertyInitializationCheck */
             self::$requestInterceptors ??= new \WeakMap();
             $requestInterceptors = self::$requestInterceptors[$request] ?? [];
diff --git a/src/Connection/Internal/Http1Parser.php b/src/Connection/Internal/Http1Parser.php
index cee0482a..7b8914b3 100644
--- a/src/Connection/Internal/Http1Parser.php
+++ b/src/Connection/Internal/Http1Parser.php
@@ -10,12 +10,17 @@
 use Amp\Http\Client\Request;
 use Amp\Http\Client\Response;
 use Amp\Http\Http1\Rfc7230;
+use Amp\Http\HttpMessage;
 use Amp\Http\HttpStatus;
 use Amp\Http\InvalidHeaderException;
 use function Amp\Http\Client\events;
 use function Amp\Http\mapHeaderPairs;
 
-/** @internal */
+/**
+ * @internal
+ *
+ * @psalm-import-type HeaderMapType from HttpMessage
+ */
 final class Http1Parser
 {
     use ForbidSerialization;
@@ -34,10 +39,6 @@ final class Http1Parser
     public const TRAILERS_START = 4;
     public const TRAILERS = 5;
 
-    private Request $request;
-
-    private Stream $stream;
-
     private ?Response $response = null;
 
     private int $state = self::AWAITING_HEADERS;
@@ -57,26 +58,20 @@ final class Http1Parser
 
     private bool $complete = false;
 
-    private int $maxHeaderBytes;
-
-    private int $maxBodyBytes;
+    private readonly int $maxHeaderBytes;
 
-    /** @var callable */
-    private $bodyDataCallback;
-
-    /** @var callable */
-    private $trailersCallback;
+    private readonly int $maxBodyBytes;
 
+    /**
+     * @param \Closure(string):void $bodyDataCallback
+     * @param \Closure(HeaderMapType):void $trailersCallback
+     */
     public function __construct(
-        Request $request,
-        Stream $stream,
-        callable $bodyDataCallback,
-        callable $trailersCallback,
+        private readonly Request $request,
+        private readonly Stream $stream,
+        private readonly \Closure $bodyDataCallback,
+        private readonly \Closure $trailersCallback,
     ) {
-        $this->request = $request;
-        $this->stream = $stream;
-        $this->bodyDataCallback = $bodyDataCallback;
-        $this->trailersCallback = $trailersCallback;
         $this->maxHeaderBytes = $request->getHeaderSizeLimit();
         $this->maxBodyBytes = $request->getBodySizeLimit();
     }
diff --git a/src/HttpClient.php b/src/HttpClient.php
index beba5096..93d7b18c 100644
--- a/src/HttpClient.php
+++ b/src/HttpClient.php
@@ -11,15 +11,13 @@
  */
 final class HttpClient implements DelegateHttpClient
 {
-    private DelegateHttpClient $httpClient;
-
-    /** @var EventListener[] */
-    private array $eventListeners;
-
-    public function __construct(DelegateHttpClient $httpClient, array $eventListeners)
-    {
-        $this->httpClient = $httpClient;
-        $this->eventListeners = $eventListeners;
+    /**
+     * @param EventListener[] $eventListeners
+     */
+    public function __construct(
+        private readonly DelegateHttpClient $httpClient,
+        private readonly array $eventListeners,
+    ) {
     }
 
     /**
@@ -32,7 +30,7 @@ public function request(Request $request, ?Cancellation $cancellation = null): R
         return processRequest(
             $request,
             $this->eventListeners,
-            fn () => $this->httpClient->request($request, $cancellation ?? new NullCancellation())
+            fn () => $this->httpClient->request($request, $cancellation ?? new NullCancellation()),
         );
     }
 }
diff --git a/src/InterceptedHttpClient.php b/src/InterceptedHttpClient.php
index 49bb2b3f..9aa2683b 100644
--- a/src/InterceptedHttpClient.php
+++ b/src/InterceptedHttpClient.php
@@ -13,21 +13,14 @@ final class InterceptedHttpClient implements DelegateHttpClient
 
     private static \WeakMap $requestInterceptors;
 
-    private DelegateHttpClient $httpClient;
-
-    private ApplicationInterceptor $interceptor;
-
-    /** @var EventListener[] */
-    private array $eventListeners;
-
+    /**
+     * @param EventListener[] $eventListeners
+     */
     public function __construct(
-        DelegateHttpClient $httpClient,
-        ApplicationInterceptor $interceptor,
-        array $eventListeners
+        private readonly DelegateHttpClient $httpClient,
+        private readonly ApplicationInterceptor $interceptor,
+        private readonly array $eventListeners,
     ) {
-        $this->httpClient = $httpClient;
-        $this->interceptor = $interceptor;
-        $this->eventListeners = $eventListeners;
     }
 
     public function request(Request $request, Cancellation $cancellation): Response
@@ -35,6 +28,7 @@ public function request(Request $request, Cancellation $cancellation): Response
         return processRequest($request, $this->eventListeners, function () use ($request, $cancellation) {
             /** @psalm-suppress RedundantPropertyInitializationCheck */
             self::$requestInterceptors ??= new \WeakMap();
+
             $requestInterceptors = self::$requestInterceptors[$request] ?? [];
             $requestInterceptors[] = $this->interceptor;
             self::$requestInterceptors[$request] = $requestInterceptors;
diff --git a/src/Interceptor/DecompressResponse.php b/src/Interceptor/DecompressResponse.php
index 0177f37c..acdddb47 100644
--- a/src/Interceptor/DecompressResponse.php
+++ b/src/Interceptor/DecompressResponse.php
@@ -17,7 +17,7 @@ final class DecompressResponse implements NetworkInterceptor
     use ForbidCloning;
     use ForbidSerialization;
 
-    private bool $hasZlib;
+    private readonly bool $hasZlib;
 
     public function __construct()
     {
diff --git a/src/Interceptor/FollowRedirects.php b/src/Interceptor/FollowRedirects.php
index e40edc65..5b05aa4a 100644
--- a/src/Interceptor/FollowRedirects.php
+++ b/src/Interceptor/FollowRedirects.php
@@ -105,9 +105,9 @@ private static function mergePaths(string $basePath, string $pathToMerge): strin
         return self::removeDotSegments(\implode('/', $parts));
     }
 
-    private int $maxRedirects;
+    private readonly int $maxRedirects;
 
-    private bool $autoReferrer;
+    private readonly bool $autoReferrer;
 
     public function __construct(int $limit, bool $autoReferrer = true)
     {
diff --git a/src/Interceptor/MatchOrigin.php b/src/Interceptor/MatchOrigin.php
index 71f2def3..129558e1 100644
--- a/src/Interceptor/MatchOrigin.php
+++ b/src/Interceptor/MatchOrigin.php
@@ -19,27 +19,26 @@ final class MatchOrigin implements ApplicationInterceptor
     use ForbidSerialization;
 
     /** @var ApplicationInterceptor[] */
-    private array $originMap = [];
-
-    private ?ApplicationInterceptor $default;
+    private readonly array $originMap;
 
     /**
      * @param ApplicationInterceptor[] $originMap
      *
      * @throws HttpException
      */
-    public function __construct(array $originMap, ?ApplicationInterceptor $default = null)
+    public function __construct(array $originMap, private readonly ?ApplicationInterceptor $default = null)
     {
+        $validatedMap = [];
         foreach ($originMap as $origin => $interceptor) {
             if (!$interceptor instanceof ApplicationInterceptor) {
                 $type = \get_debug_type($interceptor);
                 throw new HttpException('Origin map must be a map from origin to ApplicationInterceptor, got ' . $type);
             }
 
-            $this->originMap[$this->checkOrigin($origin)] = $interceptor;
+            $validatedMap[$this->checkOrigin($origin)] = $interceptor;
         }
 
-        $this->default = $default;
+        $this->originMap = $validatedMap;
     }
 
     public function request(
diff --git a/src/Interceptor/ModifyRequest.php b/src/Interceptor/ModifyRequest.php
index 241cbe18..63438fe9 100644
--- a/src/Interceptor/ModifyRequest.php
+++ b/src/Interceptor/ModifyRequest.php
@@ -17,15 +17,11 @@ class ModifyRequest implements NetworkInterceptor, ApplicationInterceptor
     use ForbidCloning;
     use ForbidSerialization;
 
-    /** @var \Closure(Request):(Request|null) */
-    private \Closure $mapper;
-
     /**
      * @param \Closure(Request):(Request|null) $mapper
      */
-    public function __construct(\Closure $mapper)
+    public function __construct(private readonly \Closure $mapper)
     {
-        $this->mapper = $mapper;
     }
 
     final public function requestViaNetwork(
diff --git a/src/Interceptor/ModifyResponse.php b/src/Interceptor/ModifyResponse.php
index a3f4eb4f..01b3d449 100644
--- a/src/Interceptor/ModifyResponse.php
+++ b/src/Interceptor/ModifyResponse.php
@@ -17,15 +17,11 @@ class ModifyResponse implements NetworkInterceptor, ApplicationInterceptor
     use ForbidCloning;
     use ForbidSerialization;
 
-    /** @var \Closure(Response):Response */
-    private \Closure $mapper;
-
     /**
      * @param \Closure(Response):Response $mapper
      */
-    public function __construct(\Closure $mapper)
+    public function __construct(private readonly \Closure $mapper)
     {
-        $this->mapper = $mapper;
     }
 
     final public function requestViaNetwork(
diff --git a/src/Interceptor/RetryRequests.php b/src/Interceptor/RetryRequests.php
index 03030450..6a616dc1 100644
--- a/src/Interceptor/RetryRequests.php
+++ b/src/Interceptor/RetryRequests.php
@@ -16,11 +16,8 @@ final class RetryRequests implements ApplicationInterceptor
     use ForbidCloning;
     use ForbidSerialization;
 
-    private int $retryLimit;
-
-    public function __construct(int $retryLimit)
+    public function __construct(private readonly int $retryLimit)
     {
-        $this->retryLimit = $retryLimit;
     }
 
     public function request(