diff --git a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
index 55db19552568e..adb05e76465da 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
@@ -609,7 +609,9 @@ private function generateProxyClasses(): array
                 $proxyCode = substr(self::stripComments($proxyCode), 5);
             }
 
-            $proxyClass = explode(' ', $this->inlineRequires ? substr($proxyCode, \strlen($code)) : $proxyCode, 3)[1];
+            $proxyClass = $this->inlineRequires ? substr($proxyCode, \strlen($code)) : $proxyCode;
+            $i = strpos($proxyClass, 'class');
+            $proxyClass = substr($proxyClass, 6 + $i, strpos($proxyClass, ' ', 7 + $i) - $i - 6);
 
             if ($this->asFiles || $this->namespace) {
                 $proxyCode .= "\nif (!\\class_exists('$proxyClass', false)) {\n    \\class_alias(__NAMESPACE__.'\\\\$proxyClass', '$proxyClass', false);\n}\n";
diff --git a/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/LazyServiceDumper.php b/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/LazyServiceDumper.php
index 7e8d7db84c041..251819a978098 100644
--- a/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/LazyServiceDumper.php
+++ b/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/LazyServiceDumper.php
@@ -105,7 +105,7 @@ public function getProxyCode(Definition $definition, ?string $id = null): string
 
         if ($asGhostObject) {
             try {
-                return 'class '.$proxyClass.ProxyHelper::generateLazyGhost($class);
+                return ($class?->isReadOnly() ? 'readonly ' : '').'class '.$proxyClass.ProxyHelper::generateLazyGhost($class);
             } catch (LogicException $e) {
                 throw new InvalidArgumentException(sprintf('Cannot generate lazy ghost for service "%s".', $id ?? $definition->getClass()), 0, $e);
             }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/LazyServiceDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/LazyServiceDumperTest.php
index 064bfc3cc82aa..2b2a3f2853e2f 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/LazyServiceDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/LazyServiceDumperTest.php
@@ -52,6 +52,15 @@ public function testInvalidClass()
         $this->expectExceptionMessage('Invalid "proxy" tag for service "stdClass": class "stdClass" doesn\'t implement "Psr\Container\ContainerInterface".');
         $dumper->getProxyCode($definition);
     }
+
+    public function testReadonlyClass()
+    {
+        $dumper = new LazyServiceDumper();
+        $definition = (new Definition(ReadonlyTest::class))->setLazy(true);
+
+        $this->assertTrue($dumper->isProxyCandidate($definition));
+        $this->assertStringContainsString('readonly class ReadonlyTestGhost', $dumper->getProxyCode($definition));
+    }
 }
 
 final class TestContainer implements ContainerInterface
@@ -66,3 +75,11 @@ public function get(string $key): string
         return $key;
     }
 }
+
+readonly class ReadonlyTest
+{
+    public function say(): string
+    {
+        return 'hello';
+    }
+}