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/Hash.php b/src/Hash.php
index e633efc..0c3a30a 100644
--- a/src/Hash.php
+++ b/src/Hash.php
@@ -17,11 +17,13 @@ enum Hash
     case sha384;
     case sha512;
 
+    #[\NoDiscard]
     public function ofFile(File $file): Value
     {
         return $this->ofContent($file->content());
     }
 
+    #[\NoDiscard]
     public function ofContent(File\Content $content): Value
     {
         return $this->ofSequence(
@@ -32,6 +34,7 @@ public function ofContent(File\Content $content): Value
     /**
      * @param Sequence<Str> $chunks
      */
+    #[\NoDiscard]
     public function ofSequence(Sequence $chunks): Value
     {
         return $chunks
@@ -45,11 +48,13 @@ public function ofSequence(Sequence $chunks): Value
     /**
      * @psalm-external-mutation-free
      */
+    #[\NoDiscard]
     public function start(): Incremental
     {
         return Incremental::start($this);
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return $this->name;
diff --git a/src/Incremental.php b/src/Incremental.php
index 09d7891..e09d86c 100644
--- a/src/Incremental.php
+++ b/src/Incremental.php
@@ -14,6 +14,7 @@ private function __construct(\HashContext $context)
         $this->context = $context;
     }
 
+    #[\NoDiscard]
     public static function start(Hash $hash): self
     {
         return new self(\hash_init($hash->toString()));
@@ -26,6 +27,7 @@ public static function start(Hash $hash): self
      *
      * @psalm-external-mutation-free
      */
+    #[\NoDiscard]
     public function add(Str $chunk): self
     {
         /** @psalm-suppress ImpureFunctionCall */
@@ -39,6 +41,7 @@ public function add(Str $chunk): self
      *
      * @psalm-external-mutation-free
      */
+    #[\NoDiscard]
     public function finish(): Value
     {
         return Value::of(\hash_final($this->context));
diff --git a/src/Value.php b/src/Value.php
index e4e6cc5..f6e9c30 100644
--- a/src/Value.php
+++ b/src/Value.php
@@ -24,6 +24,7 @@ private function __construct(string $hex)
      *
      * @param non-empty-string $hex
      */
+    #[\NoDiscard]
     public static function of(string $hex): self
     {
         return new self($hex);
@@ -32,11 +33,13 @@ public static function of(string $hex): self
     /**
      * @return non-empty-string
      */
+    #[\NoDiscard]
     public function hex(): string
     {
         return $this->hex;
     }
 
+    #[\NoDiscard]
     public function binary(): string
     {
         /** @var string */