diff --git a/src/PhpGenerator/Extractor.php b/src/PhpGenerator/Extractor.php
index 7de301fe..50164ced 100644
--- a/src/PhpGenerator/Extractor.php
+++ b/src/PhpGenerator/Extractor.php
@@ -389,8 +389,9 @@ private function setupFunction($function, Node\FunctionLike $node): void
 		$function->setReturnType($node->getReturnType() ? $this->toPhp($node->getReturnType()) : null);
 		foreach ($node->getParams() as $item) {
 			$visibility = $this->toVisibility($item->flags);
+			$isReadonly = (bool) ($item->flags & Node\Stmt\Class_::MODIFIER_READONLY);
 			$param = $visibility
-				? ($function->addPromotedParameter($item->var->name))->setVisibility($visibility)
+				? ($function->addPromotedParameter($item->var->name))->setVisibility($visibility)->setReadonly($isReadonly)
 				: $function->addParameter($item->var->name);
 			$param->setType($item->type ? $this->toPhp($item->type) : null);
 			$param->setReference($item->byRef);
diff --git a/tests/PhpGenerator/expected/Extractor.classes.81.expect b/tests/PhpGenerator/expected/Extractor.classes.81.expect
index 427d927b..831e8e31 100644
--- a/tests/PhpGenerator/expected/Extractor.classes.81.expect
+++ b/tests/PhpGenerator/expected/Extractor.classes.81.expect
@@ -27,3 +27,14 @@ class Class11
 class Attr
 {
 }
+
+class Class12
+{
+	private readonly string $bar;
+
+
+	public function __construct(private readonly string $foo)
+	{
+		$this->bar = "foobar";
+	}
+}
diff --git a/tests/PhpGenerator/fixtures/classes.81.php b/tests/PhpGenerator/fixtures/classes.81.php
index 3eeb9208..f283a3f7 100644
--- a/tests/PhpGenerator/fixtures/classes.81.php
+++ b/tests/PhpGenerator/fixtures/classes.81.php
@@ -27,3 +27,14 @@ public function bar($c = new \stdClass)
 class Attr
 {
 }
+
+class Class12
+{
+	private readonly string $bar;
+
+
+	public function __construct(private readonly string $foo)
+	{
+		$this->bar = "foobar";
+	}
+}