diff --git a/composer.json b/composer.json
index 429acfec..d36e9284 100755
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,7 @@
   "keywords": ["module", "xp"],
   "require" : {
     "xp-framework/core": "^11.0 | ^10.0",
-    "xp-framework/ast": "^8.0",
+    "xp-framework/ast": "^8.1",
     "php" : ">=7.0.0"
   },
   "require-dev" : {
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
index d7d7728f..2544977a 100755
--- a/src/main/php/lang/ast/emit/PHP.class.php
+++ b/src/main/php/lang/ast/emit/PHP.class.php
@@ -383,7 +383,7 @@ protected function emitEnum($result, $enum) {
   protected function emitClass($result, $class) {
     array_unshift($result->type, $class);
     array_unshift($result->meta, []);
-    $result->locals= [[], [], []];
+    $result->locals ?: $result->locals= [[], [], []];
 
     $class->comment && $this->emitOne($result, $class->comment);
     $class->annotations && $this->emitOne($result, $class->annotations);
@@ -399,21 +399,24 @@ protected function emitClass($result, $class) {
     if ($result->locals[2]) {
       $result->out->write('private $__virtual= [');
       foreach ($result->locals[2] as $name => $access) {
-        $result->out->write("'{$name}' => null,");
+        $name && $result->out->write("'{$name}' => null,");
       }
       $result->out->write('];');
 
       $result->out->write('public function __get($name) { switch ($name) {');
       foreach ($result->locals[2] as $name => $access) {
-        $result->out->write('case "'.$name.'":');
+        $result->out->write($name ? 'case "'.$name.'":' : 'default:');
         $this->emitOne($result, $access[0]);
         $result->out->write('break;');
       }
-      $result->out->write('default: trigger_error("Undefined property ".__CLASS__."::".$name, E_USER_WARNING); }}');
+      isset($result->locals[2][null]) || $result->out->write(
+        'default: trigger_error("Undefined property ".__CLASS__."::".$name, E_USER_WARNING);'
+      );
+      $result->out->write('}}');
 
       $result->out->write('public function __set($name, $value) { switch ($name) {');
       foreach ($result->locals[2] as $name => $access) {
-        $result->out->write('case "'.$name.'":');
+        $result->out->write($name ? 'case "'.$name.'":' : 'default:');
         $this->emitOne($result, $access[1]);
         $result->out->write('break;');
       }
@@ -433,6 +436,7 @@ protected function emitClass($result, $class) {
     $this->emitMeta($result, $class->name, $class->annotations, $class->comment);
     $result->out->write('}} '.$class->name.'::__init();');
     array_shift($result->type);
+    $result->locals= [];
   }
 
   protected function emitMeta($result, $name, $annotations, $comment) {
diff --git a/src/main/php/lang/ast/emit/PHP70.class.php b/src/main/php/lang/ast/emit/PHP70.class.php
index 6962bb4b..5d7be79e 100755
--- a/src/main/php/lang/ast/emit/PHP70.class.php
+++ b/src/main/php/lang/ast/emit/PHP70.class.php
@@ -19,6 +19,7 @@ class PHP70 extends PHP {
     OmitArgumentNames,
     OmitConstModifiers,
     OmitPropertyTypes,
+    ReadonlyClasses,
     ReadonlyProperties,
     RewriteClassOnObjects,
     RewriteEnums,
diff --git a/src/main/php/lang/ast/emit/PHP71.class.php b/src/main/php/lang/ast/emit/PHP71.class.php
index 4aabf251..8ac6ba0f 100755
--- a/src/main/php/lang/ast/emit/PHP71.class.php
+++ b/src/main/php/lang/ast/emit/PHP71.class.php
@@ -19,6 +19,7 @@ class PHP71 extends PHP {
     OmitArgumentNames,
     OmitPropertyTypes,
     ReadonlyProperties,
+    ReadonlyClasses,
     RewriteClassOnObjects,
     RewriteEnums,
     RewriteExplicitOctals,
diff --git a/src/main/php/lang/ast/emit/PHP72.class.php b/src/main/php/lang/ast/emit/PHP72.class.php
index 2c9aa978..23a0bdc6 100755
--- a/src/main/php/lang/ast/emit/PHP72.class.php
+++ b/src/main/php/lang/ast/emit/PHP72.class.php
@@ -19,6 +19,7 @@ class PHP72 extends PHP {
     OmitArgumentNames,
     OmitPropertyTypes,
     ReadonlyProperties,
+    ReadonlyClasses,
     RewriteClassOnObjects,
     RewriteEnums,
     RewriteExplicitOctals,
diff --git a/src/main/php/lang/ast/emit/PHP74.class.php b/src/main/php/lang/ast/emit/PHP74.class.php
index bf7c1e87..25e9a286 100755
--- a/src/main/php/lang/ast/emit/PHP74.class.php
+++ b/src/main/php/lang/ast/emit/PHP74.class.php
@@ -17,6 +17,7 @@ class PHP74 extends PHP {
     NonCapturingCatchVariables,
     NullsafeAsTernaries,
     OmitArgumentNames,
+    ReadonlyClasses,
     ReadonlyProperties,
     RewriteBlockLambdaExpressions,
     RewriteClassOnObjects,
diff --git a/src/main/php/lang/ast/emit/PHP80.class.php b/src/main/php/lang/ast/emit/PHP80.class.php
index 779c224c..af4026a6 100755
--- a/src/main/php/lang/ast/emit/PHP80.class.php
+++ b/src/main/php/lang/ast/emit/PHP80.class.php
@@ -9,7 +9,8 @@
  * @see  https://wiki.php.net/rfc#php_80
  */
 class PHP80 extends PHP {
-  use RewriteBlockLambdaExpressions, RewriteExplicitOctals, RewriteEnums, ReadonlyProperties, CallablesAsClosures, ArrayUnpackUsingMerge;
+  use RewriteBlockLambdaExpressions, RewriteExplicitOctals, RewriteEnums;
+  use ReadonlyClasses, ReadonlyProperties, CallablesAsClosures, ArrayUnpackUsingMerge;
 
   /** Sets up type => literal mappings */
   public function __construct() {
diff --git a/src/main/php/lang/ast/emit/PHP81.class.php b/src/main/php/lang/ast/emit/PHP81.class.php
index 1317fc28..4cc19ab2 100755
--- a/src/main/php/lang/ast/emit/PHP81.class.php
+++ b/src/main/php/lang/ast/emit/PHP81.class.php
@@ -10,7 +10,7 @@
  * @see  https://wiki.php.net/rfc#php_81
  */
 class PHP81 extends PHP {
-  use RewriteBlockLambdaExpressions;
+  use RewriteBlockLambdaExpressions, ReadonlyClasses;
 
   /** Sets up type => literal mappings */
   public function __construct() {
diff --git a/src/main/php/lang/ast/emit/PHP82.class.php b/src/main/php/lang/ast/emit/PHP82.class.php
index df654511..78dc8370 100755
--- a/src/main/php/lang/ast/emit/PHP82.class.php
+++ b/src/main/php/lang/ast/emit/PHP82.class.php
@@ -10,7 +10,7 @@
  * @see  https://wiki.php.net/rfc#php_82
  */
 class PHP82 extends PHP {
-  use RewriteBlockLambdaExpressions;
+  use RewriteBlockLambdaExpressions, ReadonlyClasses;
 
   /** Sets up type => literal mappings */
   public function __construct() {
diff --git a/src/main/php/lang/ast/emit/ReadonlyClasses.class.php b/src/main/php/lang/ast/emit/ReadonlyClasses.class.php
new file mode 100755
index 00000000..ab29f97f
--- /dev/null
+++ b/src/main/php/lang/ast/emit/ReadonlyClasses.class.php
@@ -0,0 +1,36 @@
+<?php namespace lang\ast\emit;
+
+use lang\ast\Code;
+
+/**
+ * Implements readonly properties by removing the `readonly` modifier from
+ * the class and inheriting it to all properties (and promoted constructor
+ * arguments).
+ *
+ * @see  https://wiki.php.net/rfc/readonly_classes
+ */
+trait ReadonlyClasses {
+
+  protected function emitClass($result, $class) {
+    if (false !== ($p= array_search('readonly', $class->modifiers))) {
+      unset($class->modifiers[$p]);
+
+      // Inherit
+      foreach ($class->body as $member) {
+        if ($member->is('property')) {
+          $member->modifiers[]= 'readonly';
+        } else if ($member->is('method')) {
+          foreach ($member->signature->parameters as $param) {
+            $param->promote && $param->promote.= ' readonly';
+          }
+        }
+      }
+
+      // Prevent dynamic members
+      $throw= new Code('throw new \\Error("Cannot create dynamic property ".__CLASS__."::".$name);');
+      $result->locals= [[], [], [null => [$throw, $throw]]];
+    }
+
+    return parent::emitClass($result, $class);
+  }
+}
\ No newline at end of file
diff --git a/src/test/php/lang/ast/unittest/emit/ReadonlyPropertiesTest.class.php b/src/test/php/lang/ast/unittest/emit/ReadonlyTest.class.php
similarity index 70%
rename from src/test/php/lang/ast/unittest/emit/ReadonlyPropertiesTest.class.php
rename to src/test/php/lang/ast/unittest/emit/ReadonlyTest.class.php
index 2f65771c..f13ae5a5 100755
--- a/src/test/php/lang/ast/unittest/emit/ReadonlyPropertiesTest.class.php
+++ b/src/test/php/lang/ast/unittest/emit/ReadonlyTest.class.php
@@ -4,11 +4,12 @@
 use unittest\{Assert, Expect, Test};
 
 /**
- * Readonly properties
+ * Readonly classes and properties
  *
  * @see  https://wiki.php.net/rfc/readonly_properties_v2
+ * @see  https://wiki.php.net/rfc/readonly_classes
  */
-class ReadonlyPropertiesTest extends EmittingTest {
+class ReadonlyTest extends EmittingTest {
 
   /** @return iterable */
   private function modifiers() {
@@ -20,7 +21,19 @@ private function modifiers() {
   }
 
   #[Test]
-  public function declaration() {
+  public function class_declaration() {
+    $t= $this->type('readonly class <T> {
+      public int $fixture;
+    }');
+
+    Assert::equals(
+      sprintf('public readonly int %s::$fixture', $t->getName()),
+      $t->getField('fixture')->toString()
+    );
+  }
+
+  #[Test]
+  public function property_declaration() {
     $t= $this->type('class <T> {
       public readonly int $fixture;
     }');
@@ -32,11 +45,28 @@ public function declaration() {
   }
 
   #[Test]
-  public function with_constructor_argument_promotion() {
+  public function class_with_constructor_argument_promotion() {
+    $t= $this->type('readonly class <T> {
+      public function __construct(public string $fixture) { }
+    }');
+
+    Assert::equals(
+      sprintf('public readonly string %s::$fixture', $t->getName()),
+      $t->getField('fixture')->toString()
+    );
+    Assert::equals('Test', $t->newInstance('Test')->fixture);
+  }
+
+  #[Test]
+  public function property_defined_with_constructor_argument_promotion() {
     $t= $this->type('class <T> {
       public function __construct(public readonly string $fixture) { }
     }');
 
+    Assert::equals(
+      sprintf('public readonly string %s::$fixture', $t->getName()),
+      $t->getField('fixture')->toString()
+    );
     Assert::equals('Test', $t->newInstance('Test')->fixture);
   }
 
@@ -143,4 +173,23 @@ public function cannot_have_an_initial_value() {
       public readonly string $fixture= "Test";
     }');
   }
+
+  #[Test, Expect(class: Error::class, withMessage: '/Cannot create dynamic property .+fixture/')]
+  public function cannot_read_dynamic_members_from_readonly_classes() {
+    $t= $this->type('readonly class <T> { }');
+    $t->newInstance()->fixture;
+  }
+
+  #[Test, Expect(class: Error::class, withMessage: '/Cannot create dynamic property .+fixture/')]
+  public function cannot_write_dynamic_members_from_readonly_classes() {
+    $t= $this->type('readonly class <T> { }');
+    $t->newInstance()->fixture= true;
+  }
+
+  #[Test, Ignore('Until proper error handling facilities exist')]
+  public function readonly_classes_cannot_have_static_members() {
+    $this->type('readonly class <T> {
+      public static $test;
+    }');
+  }
 }
\ No newline at end of file