diff --git a/psalm.xml b/psalm.xml
index 6b4a878..fa1d427 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -14,4 +14,7 @@
             <directory name="vendor" />
         </ignoreFiles>
     </projectFiles>
+    <issueHandlers>
+        <UndefinedAttributeClass errorLevel="suppress" />
+    </issueHandlers>
 </psalm>
diff --git a/src/ClientError.php b/src/ClientError.php
index 51d1db5..5237fa4 100644
--- a/src/ClientError.php
+++ b/src/ClientError.php
@@ -8,6 +8,9 @@
     Response,
 };
 
+/**
+ * @psalm-immutable
+ */
 final class ClientError
 {
     private Request $request;
@@ -23,11 +26,13 @@ public function __construct(Request $request, Response $response)
         $this->response = $response;
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function response(): Response
     {
         return $this->response;
diff --git a/src/ConnectionFailed.php b/src/ConnectionFailed.php
index 4b818fe..96d7713 100644
--- a/src/ConnectionFailed.php
+++ b/src/ConnectionFailed.php
@@ -5,6 +5,9 @@
 
 use Innmind\Http\Request;
 
+/**
+ * @psalm-immutable
+ */
 final class ConnectionFailed
 {
     public function __construct(
@@ -13,11 +16,13 @@ public function __construct(
     ) {
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function reason(): string
     {
         return $this->reason;
diff --git a/src/Curl.php b/src/Curl.php
index a484ee8..c4eda29 100644
--- a/src/Curl.php
+++ b/src/Curl.php
@@ -79,6 +79,7 @@ public static function of(
      *
      * @param positive-int $max
      */
+    #[\NoDiscard]
     public function maxConcurrency(int $max): self
     {
         return new self(
@@ -98,6 +99,7 @@ public function maxConcurrency(int $max): self
      * @param Period $timeout Only seconds are allowed
      * @param callable(): void $heartbeat
      */
+    #[\NoDiscard]
     public function heartbeat(Period $timeout, ?callable $heartbeat = null): self
     {
         return new self(
@@ -120,6 +122,7 @@ public function heartbeat(Period $timeout, ?callable $heartbeat = null): self
      *
      * @psalm-mutation-free
      */
+    #[\NoDiscard]
     public function disableSSLVerification(): self
     {
         return new self(
@@ -136,6 +139,7 @@ public function disableSSLVerification(): self
     /**
      * @psalm-mutation-free
      */
+    #[\NoDiscard]
     public function proxy(Url $proxy): self
     {
         return new self(
diff --git a/src/Failure.php b/src/Failure.php
index 5eb4b3d..d94a710 100644
--- a/src/Failure.php
+++ b/src/Failure.php
@@ -5,6 +5,9 @@
 
 use Innmind\Http\Request;
 
+/**
+ * @psalm-immutable
+ */
 final class Failure
 {
     public function __construct(
@@ -13,11 +16,13 @@ public function __construct(
     ) {
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function reason(): string
     {
         return $this->reason;
diff --git a/src/Information.php b/src/Information.php
index aaf7777..aa7040c 100644
--- a/src/Information.php
+++ b/src/Information.php
@@ -8,6 +8,9 @@
     Response,
 };
 
+/**
+ * @psalm-immutable
+ */
 final class Information
 {
     private Request $request;
@@ -23,11 +26,13 @@ public function __construct(Request $request, Response $response)
         $this->response = $response;
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function response(): Response
     {
         return $this->response;
diff --git a/src/MalformedResponse.php b/src/MalformedResponse.php
index 99945c8..dc5d94d 100644
--- a/src/MalformedResponse.php
+++ b/src/MalformedResponse.php
@@ -6,6 +6,9 @@
 use Innmind\HttpTransport\MalformedResponse\Raw;
 use Innmind\Http\Request;
 
+/**
+ * @psalm-immutable
+ */
 final class MalformedResponse
 {
     private Request $request;
@@ -17,11 +20,13 @@ public function __construct(Request $request, ?Raw $raw = null)
         $this->raw = $raw ?? Raw::none();
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function raw(): Raw
     {
         return $this->raw;
diff --git a/src/MalformedResponse/Raw.php b/src/MalformedResponse/Raw.php
index d59a768..5908358 100644
--- a/src/MalformedResponse/Raw.php
+++ b/src/MalformedResponse/Raw.php
@@ -42,6 +42,7 @@ public static function none(): self
         return new self(Str::of(''), Sequence::of(), Content::none());
     }
 
+    #[\NoDiscard]
     public function statusLine(): Str
     {
         return $this->statusLine;
@@ -50,11 +51,13 @@ public function statusLine(): Str
     /**
      * @return Sequence<Str>
      */
+    #[\NoDiscard]
     public function headers(): Sequence
     {
         return $this->headers;
     }
 
+    #[\NoDiscard]
     public function body(): Content
     {
         return $this->body;
diff --git a/src/Redirection.php b/src/Redirection.php
index 91601c7..cc7d357 100644
--- a/src/Redirection.php
+++ b/src/Redirection.php
@@ -8,6 +8,9 @@
     Response,
 };
 
+/**
+ * @psalm-immutable
+ */
 final class Redirection
 {
     private Request $request;
@@ -23,11 +26,13 @@ public function __construct(Request $request, Response $response)
         $this->response = $response;
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function response(): Response
     {
         return $this->response;
diff --git a/src/ServerError.php b/src/ServerError.php
index 503345a..f481558 100644
--- a/src/ServerError.php
+++ b/src/ServerError.php
@@ -8,6 +8,9 @@
     Response,
 };
 
+/**
+ * @psalm-immutable
+ */
 final class ServerError
 {
     private Request $request;
@@ -23,11 +26,13 @@ public function __construct(Request $request, Response $response)
         $this->response = $response;
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function response(): Response
     {
         return $this->response;
diff --git a/src/Success.php b/src/Success.php
index a3fffc5..d09bb9d 100644
--- a/src/Success.php
+++ b/src/Success.php
@@ -8,6 +8,9 @@
     Response,
 };
 
+/**
+ * @psalm-immutable
+ */
 final class Success
 {
     private Request $request;
@@ -23,11 +26,13 @@ public function __construct(Request $request, Response $response)
         $this->response = $response;
     }
 
+    #[\NoDiscard]
     public function request(): Request
     {
         return $this->request;
     }
 
+    #[\NoDiscard]
     public function response(): Response
     {
         return $this->response;
diff --git a/src/Transport.php b/src/Transport.php
index 227e16d..5e482fa 100644
--- a/src/Transport.php
+++ b/src/Transport.php
@@ -14,5 +14,6 @@ interface Transport
     /**
      * @return Either<Errors, Success>
      */
+    #[\NoDiscard]
     public function __invoke(Request $request): Either;
 }