diff --git a/src/CompiledInjector.php b/src/CompiledInjector.php
index 9dfcd114..77f1e0ab 100644
--- a/src/CompiledInjector.php
+++ b/src/CompiledInjector.php
@@ -8,6 +8,7 @@
 use Ray\Compiler\Exception\ScriptDirNotReadable;
 use Ray\Compiler\Exception\Unbound;
 use Ray\Di\Annotation\ScriptDir;
+use Ray\Di\InjectorInterface;
 use Ray\Di\Name;
 
 use function file_exists;
@@ -66,11 +67,13 @@ public function __construct(#[ScriptDir]
 
         /** @psalm-var ScriptDir $realPath */
         $this->scriptDir = $realPath;
+        $this->cacheInjector();
         $this->registerLoader();
     }
 
     public function __wakeup()
     {
+        $this->cacheInjector();
         $this->registerLoader();
     }
 
@@ -105,6 +108,11 @@ public function getInstance($interface, $name = Name::ANY)
         return $instance;
     }
 
+    private function cacheInjector(): void
+    {
+        $this->singletons[InjectorInterface::class . '-' . Name::ANY] = $this;
+    }
+
     private function registerLoader(): void
     {
         $scriptDir = $this->scriptDir;
diff --git a/src/InstanceScript.php b/src/InstanceScript.php
index fd2f068b..8c98a84b 100644
--- a/src/InstanceScript.php
+++ b/src/InstanceScript.php
@@ -158,7 +158,7 @@ public function pushAspectBind(AopBind $aopBind): void
     public function getScript(string|null $postConstruct, bool $isSingleton): string
     {
         if (is_string($postConstruct)) {
-            $this->laterLines[] = sprintf('$instance->%s();', $postConstruct);
+            $this->pushPostConstruct($postConstruct, $isSingleton);
         }
 
         if ($this->implementsSetContext) {
@@ -166,7 +166,7 @@ public function getScript(string|null $postConstruct, bool $isSingleton): string
         }
 
         $this->laterLines[] = self::COMMENT;
-        if ($isSingleton) {
+        if ($isSingleton && ! is_string($postConstruct)) {
             $this->laterLines[] = '$singletons[$dependencyIndex] = $instance;';
         }
 
@@ -178,4 +178,21 @@ public function getScript(string|null $postConstruct, bool $isSingleton): string
 
         return $script;
     }
+
+    private function pushPostConstruct(string $postConstruct, bool $isSingleton): void
+    {
+        if (! $isSingleton) {
+            $this->laterLines[] = sprintf('$instance->%s();', $postConstruct);
+
+            return;
+        }
+
+        $this->laterLines[] = '$singletons[$dependencyIndex] = $instance;';
+        $this->laterLines[] = 'try {';
+        $this->laterLines[] = sprintf('    $instance->%s();', $postConstruct);
+        $this->laterLines[] = '} catch (\Throwable $e) {';
+        $this->laterLines[] = '    unset($singletons[$dependencyIndex]);';
+        $this->laterLines[] = '    throw $e;';
+        $this->laterLines[] = '}';
+    }
 }
diff --git a/tests/Fake/FakeFailingPostConstructSingleton.php b/tests/Fake/FakeFailingPostConstructSingleton.php
new file mode 100644
index 00000000..735b7276
--- /dev/null
+++ b/tests/Fake/FakeFailingPostConstructSingleton.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ray\Compiler;
+
+use Ray\Di\Di\PostConstruct;
+use RuntimeException;
+
+final class FakeFailingPostConstructSingleton
+{
+    public static int $constructorCalls = 0;
+    public static int $postConstructCalls = 0;
+    public bool $initialized = false;
+
+    public function __construct()
+    {
+        self::$constructorCalls++;
+    }
+
+    #[PostConstruct]
+    public function initialize(): void
+    {
+        self::$postConstructCalls++;
+        if (self::$postConstructCalls === 1) {
+            throw new RuntimeException('PostConstruct failed');
+        }
+
+        $this->initialized = true;
+    }
+
+    public static function reset(): void
+    {
+        self::$constructorCalls = 0;
+        self::$postConstructCalls = 0;
+    }
+}
diff --git a/tests/Fake/FakePostConstructDependent.php b/tests/Fake/FakePostConstructDependent.php
new file mode 100644
index 00000000..d441bba7
--- /dev/null
+++ b/tests/Fake/FakePostConstructDependent.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ray\Compiler;
+
+final class FakePostConstructDependent
+{
+    public function __construct(public readonly FakePostConstructSingleton $singleton)
+    {
+    }
+}
diff --git a/tests/Fake/FakePostConstructSingleton.php b/tests/Fake/FakePostConstructSingleton.php
new file mode 100644
index 00000000..aa84a08e
--- /dev/null
+++ b/tests/Fake/FakePostConstructSingleton.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ray\Compiler;
+
+use Ray\Di\Di\PostConstruct;
+use Ray\Di\InjectorInterface;
+use RuntimeException;
+
+use function assert;
+
+final class FakePostConstructSingleton
+{
+    public static int $postConstructCalls = 0;
+    public FakePostConstructDependent|null $dependent = null;
+
+    public function __construct(private readonly InjectorInterface $injector)
+    {
+    }
+
+    #[PostConstruct]
+    public function initialize(): void
+    {
+        self::$postConstructCalls++;
+        if (self::$postConstructCalls > 1) {
+            throw new RuntimeException('Recursive PostConstruct call');
+        }
+
+        $dependent = $this->injector->getInstance(FakePostConstructDependent::class);
+        assert($dependent instanceof FakePostConstructDependent);
+        $this->dependent = $dependent;
+    }
+
+    public static function reset(): void
+    {
+        self::$postConstructCalls = 0;
+    }
+}
diff --git a/tests/SingletonPostConstructTest.php b/tests/SingletonPostConstructTest.php
new file mode 100644
index 00000000..45d9dab0
--- /dev/null
+++ b/tests/SingletonPostConstructTest.php
@@ -0,0 +1,69 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Ray\Compiler;
+
+use PHPUnit\Framework\TestCase;
+use Ray\Di\AbstractModule;
+use Ray\Di\InjectorInterface;
+use Ray\Di\Scope;
+use RuntimeException;
+
+use function is_dir;
+use function mkdir;
+
+final class SingletonPostConstructTest extends TestCase
+{
+    private CompiledInjector $injector;
+
+    protected function setUp(): void
+    {
+        $scriptDir = __DIR__ . '/tmp/singleton-post-construct';
+        if (! is_dir($scriptDir)) {
+            mkdir($scriptDir, 0777, true);
+        }
+
+        deleteFiles($scriptDir);
+        FakeFailingPostConstructSingleton::reset();
+        FakePostConstructSingleton::reset();
+
+        $module = new class extends AbstractModule {
+            protected function configure(): void
+            {
+                $this->bind(FakePostConstructSingleton::class)->in(Scope::SINGLETON);
+                $this->bind(FakePostConstructDependent::class);
+                $this->bind(FakeFailingPostConstructSingleton::class)->in(Scope::SINGLETON);
+            }
+        };
+        (new Compiler())->compile($module, $scriptDir);
+        $this->injector = new CompiledInjector($scriptDir);
+    }
+
+    public function testSingletonIsAvailableDuringPostConstruct(): void
+    {
+        $singleton = $this->injector->getInstance(FakePostConstructSingleton::class);
+        $this->assertInstanceOf(FakePostConstructSingleton::class, $singleton);
+        $this->assertInstanceOf(FakePostConstructDependent::class, $singleton->dependent);
+        $this->assertSame($singleton, $singleton->dependent->singleton);
+        $this->assertSame(1, FakePostConstructSingleton::$postConstructCalls);
+        $this->assertSame($this->injector, $this->injector->getInstance(InjectorInterface::class));
+    }
+
+    public function testFailedPostConstructIsRemovedFromSingletonCache(): void
+    {
+        try {
+            $this->injector->getInstance(FakeFailingPostConstructSingleton::class);
+            $this->fail('The first PostConstruct call must fail.');
+        } catch (RuntimeException $e) {
+            $this->assertSame('PostConstruct failed', $e->getMessage());
+        }
+
+        $singleton = $this->injector->getInstance(FakeFailingPostConstructSingleton::class);
+        $this->assertInstanceOf(FakeFailingPostConstructSingleton::class, $singleton);
+        $this->assertTrue($singleton->initialized);
+        $this->assertSame(2, FakeFailingPostConstructSingleton::$constructorCalls);
+        $this->assertSame(2, FakeFailingPostConstructSingleton::$postConstructCalls);
+        $this->assertSame($singleton, $this->injector->getInstance(FakeFailingPostConstructSingleton::class));
+    }
+}