diff --git a/psalm.xml b/psalm.xml
index 510148d..feccc34 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/EnvironmentPath.php b/src/EnvironmentPath.php
index a59edbb..9eceb10 100644
--- a/src/EnvironmentPath.php
+++ b/src/EnvironmentPath.php
@@ -16,11 +16,13 @@ private function __construct(
     /**
      * @psalm-pure
      */
+    #[\NoDiscard]
     public static function of(string $value): self
     {
         return new self($value);
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return $this->value;
diff --git a/src/Server.php b/src/Server.php
index c204219..43bd72b 100644
--- a/src/Server.php
+++ b/src/Server.php
@@ -27,6 +27,7 @@ private function __construct(
     ) {
     }
 
+    #[\NoDiscard]
     public static function osx(
         Clock $clock,
         Control $control,
@@ -35,6 +36,7 @@ public static function osx(
         return new self(OSX::of($clock, $control, $path));
     }
 
+    #[\NoDiscard]
     public static function linux(
         Clock $clock,
         Control $control,
@@ -42,6 +44,7 @@ public static function linux(
         return new self(Linux::of($clock, $control));
     }
 
+    #[\NoDiscard]
     public static function logger(self $server, LoggerInterface $logger): self
     {
         return new self(Logger::of(
@@ -53,6 +56,7 @@ public static function logger(self $server, LoggerInterface $logger): self
     /**
      * @return Attempt<Cpu>
      */
+    #[\NoDiscard]
     public function cpu(): Attempt
     {
         return $this->implementation->cpu();
@@ -61,11 +65,13 @@ public function cpu(): Attempt
     /**
      * @return Attempt<Memory>
      */
+    #[\NoDiscard]
     public function memory(): Attempt
     {
         return $this->implementation->memory();
     }
 
+    #[\NoDiscard]
     public function processes(): Processes
     {
         return $this->implementation->processes();
@@ -74,16 +80,19 @@ public function processes(): Processes
     /**
      * @return Attempt<LoadAverage>
      */
+    #[\NoDiscard]
     public function loadAverage(): Attempt
     {
         return $this->implementation->loadAverage();
     }
 
+    #[\NoDiscard]
     public function disk(): Disk
     {
         return $this->implementation->disk();
     }
 
+    #[\NoDiscard]
     public function tmp(): Path
     {
         return Path::of(\rtrim(\sys_get_temp_dir(), '/').'/');
diff --git a/src/Server/Cpu.php b/src/Server/Cpu.php
index 9142bd0..cf184d2 100644
--- a/src/Server/Cpu.php
+++ b/src/Server/Cpu.php
@@ -34,26 +34,31 @@ public static function of(
         return new self($user, $system, $idle, $cores);
     }
 
+    #[\NoDiscard]
     public function user(): Percentage
     {
         return $this->user;
     }
 
+    #[\NoDiscard]
     public function system(): Percentage
     {
         return $this->system;
     }
 
+    #[\NoDiscard]
     public function idle(): Percentage
     {
         return $this->idle;
     }
 
+    #[\NoDiscard]
     public function cores(): Cores
     {
         return $this->cores;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return \sprintf(
diff --git a/src/Server/Cpu/Cores.php b/src/Server/Cpu/Cores.php
index 029e7ab..57bfef3 100644
--- a/src/Server/Cpu/Cores.php
+++ b/src/Server/Cpu/Cores.php
@@ -30,11 +30,13 @@ public static function of(int $value): self
     /**
      * @return int<1, max>
      */
+    #[\NoDiscard]
     public function toInt(): int
     {
         return $this->value;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return (string) $this->value;
diff --git a/src/Server/Cpu/Percentage.php b/src/Server/Cpu/Percentage.php
index 869da66..2f6fd21 100644
--- a/src/Server/Cpu/Percentage.php
+++ b/src/Server/Cpu/Percentage.php
@@ -31,11 +31,13 @@ public static function maybe(float $value): Maybe
         return Maybe::just(new self($value));
     }
 
+    #[\NoDiscard]
     public function toFloat(): float
     {
         return $this->value;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return \sprintf(
diff --git a/src/Server/Disk.php b/src/Server/Disk.php
index 3265fc9..194113f 100644
--- a/src/Server/Disk.php
+++ b/src/Server/Disk.php
@@ -46,6 +46,7 @@ public static function logger(self $disk, LoggerInterface $logger): self
     /**
      * @return Sequence<Volume>
      */
+    #[\NoDiscard]
     public function volumes(): Sequence
     {
         return $this->implementation->volumes();
@@ -54,6 +55,7 @@ public function volumes(): Sequence
     /**
      * @return Maybe<Volume>
      */
+    #[\NoDiscard]
     public function get(MountPoint $point): Maybe
     {
         return $this->implementation->get($point);
diff --git a/src/Server/Disk/Volume.php b/src/Server/Disk/Volume.php
index e4f09cd..bf6ad1b 100644
--- a/src/Server/Disk/Volume.php
+++ b/src/Server/Disk/Volume.php
@@ -37,26 +37,31 @@ public static function of(
         return new self($mountPoint, $size, $available, $used, $usage);
     }
 
+    #[\NoDiscard]
     public function mountPoint(): MountPoint
     {
         return $this->mountPoint;
     }
 
+    #[\NoDiscard]
     public function size(): Bytes
     {
         return $this->size;
     }
 
+    #[\NoDiscard]
     public function available(): Bytes
     {
         return $this->available;
     }
 
+    #[\NoDiscard]
     public function used(): Bytes
     {
         return $this->used;
     }
 
+    #[\NoDiscard]
     public function usage(): Usage
     {
         return $this->usage;
diff --git a/src/Server/Disk/Volume/MountPoint.php b/src/Server/Disk/Volume/MountPoint.php
index b2bc9aa..6c07714 100644
--- a/src/Server/Disk/Volume/MountPoint.php
+++ b/src/Server/Disk/Volume/MountPoint.php
@@ -27,11 +27,13 @@ public static function of(string $value): self
         return new self($value);
     }
 
+    #[\NoDiscard]
     public function equals(self $point): bool
     {
         return $point->is($this->value);
     }
 
+    #[\NoDiscard]
     public function is(string $point): bool
     {
         return $this->value === $point;
@@ -40,6 +42,7 @@ public function is(string $point): bool
     /**
      * @return non-empty-string
      */
+    #[\NoDiscard]
     public function toString(): string
     {
         return $this->value;
diff --git a/src/Server/Disk/Volume/Usage.php b/src/Server/Disk/Volume/Usage.php
index 271e4d2..c3b7d29 100644
--- a/src/Server/Disk/Volume/Usage.php
+++ b/src/Server/Disk/Volume/Usage.php
@@ -31,11 +31,13 @@ public static function maybe(float $value): Maybe
         return Maybe::just(new self($value));
     }
 
+    #[\NoDiscard]
     public function toFloat(): float
     {
         return $this->value;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return \sprintf(
diff --git a/src/Server/LoadAverage.php b/src/Server/LoadAverage.php
index e9a99c6..18856ee 100644
--- a/src/Server/LoadAverage.php
+++ b/src/Server/LoadAverage.php
@@ -36,16 +36,19 @@ public static function maybe(
         return Maybe::just(new self($lastMinute, $lastFiveMinutes, $lastFifteenMinutes));
     }
 
+    #[\NoDiscard]
     public function lastMinute(): float
     {
         return $this->lastMinute;
     }
 
+    #[\NoDiscard]
     public function lastFiveMinutes(): float
     {
         return $this->lastFiveMinutes;
     }
 
+    #[\NoDiscard]
     public function lastFifteenMinutes(): float
     {
         return $this->lastFifteenMinutes;
diff --git a/src/Server/Memory.php b/src/Server/Memory.php
index 0af8b99..6bf5abf 100644
--- a/src/Server/Memory.php
+++ b/src/Server/Memory.php
@@ -33,26 +33,31 @@ public static function of(
         return new self($total, $active, $free, $swap, $used);
     }
 
+    #[\NoDiscard]
     public function total(): Bytes
     {
         return $this->total;
     }
 
+    #[\NoDiscard]
     public function active(): Bytes
     {
         return $this->active;
     }
 
+    #[\NoDiscard]
     public function free(): Bytes
     {
         return $this->free;
     }
 
+    #[\NoDiscard]
     public function swap(): Bytes
     {
         return $this->swap;
     }
 
+    #[\NoDiscard]
     public function used(): Bytes
     {
         return $this->used;
diff --git a/src/Server/Memory/Bytes.php b/src/Server/Memory/Bytes.php
index 2273bf5..10fb202 100644
--- a/src/Server/Memory/Bytes.php
+++ b/src/Server/Memory/Bytes.php
@@ -44,11 +44,13 @@ public static function of(int $value): self
     /**
      * @return int<0, max>
      */
+    #[\NoDiscard]
     public function toInt(): int
     {
         return $this->value;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return Size::of($this->value)->toString();
diff --git a/src/Server/Process.php b/src/Server/Process.php
index 38db37c..211766c 100644
--- a/src/Server/Process.php
+++ b/src/Server/Process.php
@@ -48,21 +48,25 @@ public static function of(
         return new self($pid, $user, $cpu, $memory, $start, $command);
     }
 
+    #[\NoDiscard]
     public function pid(): Pid
     {
         return $this->pid;
     }
 
+    #[\NoDiscard]
     public function user(): User
     {
         return $this->user;
     }
 
+    #[\NoDiscard]
     public function cpu(): Percentage
     {
         return $this->cpu;
     }
 
+    #[\NoDiscard]
     public function memory(): Memory
     {
         return $this->memory;
@@ -71,11 +75,13 @@ public function memory(): Memory
     /**
      * @return Maybe<Point>
      */
+    #[\NoDiscard]
     public function start(): Maybe
     {
         return $this->start;
     }
 
+    #[\NoDiscard]
     public function command(): Command
     {
         return $this->command;
diff --git a/src/Server/Process/Command.php b/src/Server/Process/Command.php
index e341991..24c0d31 100644
--- a/src/Server/Process/Command.php
+++ b/src/Server/Process/Command.php
@@ -32,6 +32,7 @@ public static function of(string $value): self
         return new self($value);
     }
 
+    #[\NoDiscard]
     public function matches(RegExp $pattern): bool
     {
         return $pattern->matches(Str::of($this->value));
@@ -40,6 +41,7 @@ public function matches(RegExp $pattern): bool
     /**
      * @return non-empty-string
      */
+    #[\NoDiscard]
     public function toString(): string
     {
         return $this->value;
diff --git a/src/Server/Process/Memory.php b/src/Server/Process/Memory.php
index d68cf3b..7c431a5 100644
--- a/src/Server/Process/Memory.php
+++ b/src/Server/Process/Memory.php
@@ -31,11 +31,13 @@ public static function maybe(float $value): Maybe
         return Maybe::just(new self($value));
     }
 
+    #[\NoDiscard]
     public function toFloat(): float
     {
         return $this->value;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return \sprintf(
diff --git a/src/Server/Process/Pid.php b/src/Server/Process/Pid.php
index 96b4b03..9107deb 100644
--- a/src/Server/Process/Pid.php
+++ b/src/Server/Process/Pid.php
@@ -27,11 +27,13 @@ public static function of(int $value): self
         return new self($value);
     }
 
+    #[\NoDiscard]
     public function equals(self $pid): bool
     {
         return $pid->is($this->value);
     }
 
+    #[\NoDiscard]
     public function is(int $value): bool
     {
         return $this->value === $value;
@@ -40,11 +42,13 @@ public function is(int $value): bool
     /**
      * @return int<1, max>
      */
+    #[\NoDiscard]
     public function toInt(): int
     {
         return $this->value;
     }
 
+    #[\NoDiscard]
     public function toString(): string
     {
         return (string) $this->value;
diff --git a/src/Server/Process/User.php b/src/Server/Process/User.php
index 712a802..db7af58 100644
--- a/src/Server/Process/User.php
+++ b/src/Server/Process/User.php
@@ -30,6 +30,7 @@ public static function of(string $value): self
     /**
      * @return non-empty-string
      */
+    #[\NoDiscard]
     public function toString(): string
     {
         return $this->value;
diff --git a/src/Server/Processes.php b/src/Server/Processes.php
index b28bb74..eec6b2a 100644
--- a/src/Server/Processes.php
+++ b/src/Server/Processes.php
@@ -54,6 +54,7 @@ public static function logger(self $processes, LoggerInterface $logger): self
     /**
      * @return Sequence<Process>
      */
+    #[\NoDiscard]
     public function all(): Sequence
     {
         return $this->implementation->all();
@@ -62,6 +63,7 @@ public function all(): Sequence
     /**
      * @return Maybe<Process>
      */
+    #[\NoDiscard]
     public function get(Pid $pid): Maybe
     {
         return $this->implementation->get($pid);
diff --git a/src/ServerFactory.php b/src/ServerFactory.php
index eb64076..367ac75 100644
--- a/src/ServerFactory.php
+++ b/src/ServerFactory.php
@@ -8,6 +8,7 @@
 
 final class ServerFactory
 {
+    #[\NoDiscard]
     public static function build(
         Clock $clock,
         Control $control,