diff --git a/Zend/tests/readonly_classes/readonly_class_inheritance_success.phpt b/Zend/tests/readonly_classes/readonly_class_inheritance_success.phpt
index 33e73554ce01..133152ca6e91 100644
--- a/Zend/tests/readonly_classes/readonly_class_inheritance_success.phpt
+++ b/Zend/tests/readonly_classes/readonly_class_inheritance_success.phpt
@@ -5,11 +5,22 @@ Readonly class can extend a readonly class
 
 readonly class Foo
 {
+    public int $prop = 1;
 }
 
 readonly class Bar extends Foo
 {
+    public int $prop = 2;
 }
 
+readonly class Baz extends Foo {}
+
+var_dump(new Foo()->prop);
+var_dump(new Bar()->prop);
+var_dump(new Baz()->prop);
+
 ?>
 --EXPECT--
+int(1)
+int(2)
+int(1)
diff --git a/Zend/tests/readonly_classes/readonly_with_property_default.phpt b/Zend/tests/readonly_classes/readonly_with_property_default.phpt
new file mode 100644
index 000000000000..4268ff5734a4
--- /dev/null
+++ b/Zend/tests/readonly_classes/readonly_with_property_default.phpt
@@ -0,0 +1,36 @@
+--TEST--
+Properties of a readonly class may have default values
+--FILE--
+<?php
+
+readonly class Foo
+{
+    public int $bar = 1;
+    public ?string $nullable = null;
+
+    public function __construct()
+    {
+        try {
+            $this->bar = 2;
+        } catch (Error $e) {
+            echo $e::class, ": ", $e->getMessage(), "\n";
+        }
+    }
+}
+
+$foo = new Foo();
+var_dump($foo->bar);
+var_dump($foo->nullable);
+
+try {
+    $foo->bar = 3;
+} catch (Error $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Error: Cannot modify readonly property Foo::$bar
+int(1)
+NULL
+Error: Cannot modify readonly property Foo::$bar
diff --git a/Zend/tests/readonly_classes/readonly_with_property_default_trait.phpt b/Zend/tests/readonly_classes/readonly_with_property_default_trait.phpt
new file mode 100644
index 000000000000..e96945e0992e
--- /dev/null
+++ b/Zend/tests/readonly_classes/readonly_with_property_default_trait.phpt
@@ -0,0 +1,18 @@
+--TEST--
+Readonly class may use readonly trait property with default value
+--FILE--
+<?php
+
+trait TDefault {
+    public readonly int $prop = 2;
+}
+
+readonly class C {
+    use TDefault;
+}
+
+var_dump(new C()->prop);
+
+?>
+--EXPECT--
+int(2)
diff --git a/Zend/tests/readonly_props/readonly_clone_success1.phpt b/Zend/tests/readonly_props/readonly_clone_success1.phpt
index 72cd9e9622b3..ab6ee3157332 100644
--- a/Zend/tests/readonly_props/readonly_clone_success1.phpt
+++ b/Zend/tests/readonly_props/readonly_clone_success1.phpt
@@ -23,6 +23,24 @@ var_dump($foo2);
 
 var_dump(clone $foo2);
 
+class FooWithDefault {
+    public readonly int $bar = 1;
+
+    public function __clone()
+    {
+        $this->bar++;
+    }
+}
+
+$fooWithDefault = new FooWithDefault();
+
+var_dump(clone $fooWithDefault);
+
+$fooWithDefault2 = clone $fooWithDefault;
+var_dump($fooWithDefault2);
+
+var_dump(clone $fooWithDefault2);
+
 ?>
 --EXPECTF--
 object(Foo)#%d (%d) {
@@ -37,3 +55,15 @@ object(Foo)#%d (%d) {
   ["bar"]=>
   int(3)
 }
+object(FooWithDefault)#%d (%d) {
+  ["bar"]=>
+  int(2)
+}
+object(FooWithDefault)#%d (%d) {
+  ["bar"]=>
+  int(2)
+}
+object(FooWithDefault)#%d (%d) {
+  ["bar"]=>
+  int(3)
+}
diff --git a/Zend/tests/readonly_props/readonly_modification.phpt b/Zend/tests/readonly_props/readonly_modification.phpt
index bd04a203be19..2e13ad3fb408 100644
--- a/Zend/tests/readonly_props/readonly_modification.phpt
+++ b/Zend/tests/readonly_props/readonly_modification.phpt
@@ -14,6 +14,18 @@ class Test {
     }
 }
 
+class TestWithDefault {
+    public readonly int $prop = 1;
+
+    public function __construct() {
+        try {
+            $this->prop = 2;
+        } catch (Error $e) {
+            echo $e::class, ": ", $e->getMessage(), "\n";
+        }
+    }
+}
+
 function byRef(&$ref) {}
 
 $test = new Test;
@@ -66,6 +78,8 @@ try {
     echo $e->getMessage(), "\n";
 }
 
+var_dump(new TestWithDefault()->prop);
+
 ?>
 --EXPECT--
 int(1)
@@ -80,3 +94,5 @@ array(0) {
 }
 Cannot indirectly modify readonly property Test::$prop2
 Cannot indirectly modify readonly property Test::$prop2
+Error: Cannot modify readonly property TestWithDefault::$prop
+int(1)
diff --git a/Zend/tests/readonly_props/readonly_trait_match.phpt b/Zend/tests/readonly_props/readonly_trait_match.phpt
index 00aa6349aa14..36f2e11ec2bc 100644
--- a/Zend/tests/readonly_props/readonly_trait_match.phpt
+++ b/Zend/tests/readonly_props/readonly_trait_match.phpt
@@ -13,7 +13,20 @@ class C {
     use T1, T2;
 }
 
+trait TDefault1 {
+    public readonly int $prop = 1;
+}
+trait TDefault2 {
+    public readonly int $prop = 1;
+}
+class CDefault {
+    use TDefault1, TDefault2;
+}
+
+var_dump(new CDefault()->prop);
+
 ?>
 ===DONE===
 --EXPECT--
+int(1)
 ===DONE===
diff --git a/Zend/tests/readonly_props/readonly_with_default.phpt b/Zend/tests/readonly_props/readonly_with_default.phpt
index 12afe5cde153..f8e381576e56 100644
--- a/Zend/tests/readonly_props/readonly_with_default.phpt
+++ b/Zend/tests/readonly_props/readonly_with_default.phpt
@@ -3,17 +3,43 @@ Readonly property with default value
 --FILE--
 <?php
 
+enum E {
+    case Case;
+}
+
 class Test {
     public readonly int $prop = 1;
+    public readonly string $className = self::class;
+    public readonly ?string $nullable = null;
+    public readonly array $array = [1, "two" => 2];
+    public readonly E $enum = E::Case;
+    public readonly string $enumString = E::Case->name;
 }
 
 $test = new Test;
+var_dump($test->prop);
+var_dump($test->className);
+var_dump($test->nullable);
+var_dump($test->array);
+var_dump($test->enum);
+var_dump($test->enumString);
 try {
     $test->prop = 2;
 } catch (Error $e) {
-    echo $e->getMessage(), "\n";
+    echo $e::class, ": ", $e->getMessage(), "\n";
 }
 
 ?>
---EXPECTF--
-Fatal error: Readonly property Test::$prop cannot have default value in %s on line %d
+--EXPECT--
+int(1)
+string(4) "Test"
+NULL
+array(2) {
+  [0]=>
+  int(1)
+  ["two"]=>
+  int(2)
+}
+enum(E::Case)
+string(4) "Case"
+Error: Cannot modify readonly property Test::$prop
diff --git a/Zend/tests/readonly_props/readonly_with_default_asymmetric_visibility.phpt b/Zend/tests/readonly_props/readonly_with_default_asymmetric_visibility.phpt
new file mode 100644
index 000000000000..a61373edc388
--- /dev/null
+++ b/Zend/tests/readonly_props/readonly_with_default_asymmetric_visibility.phpt
@@ -0,0 +1,33 @@
+--TEST--
+Readonly property with default value and asymmetric visibility
+--FILE--
+<?php
+
+class Test {
+    public readonly int $default = 1;
+    public private(set) readonly int $private = 2;
+    public protected(set) readonly int $protected = 3;
+    public public(set) readonly int $public = 4;
+}
+
+$test = new Test();
+var_dump($test->default, $test->private, $test->protected, $test->public);
+
+foreach (['default', 'private', 'protected', 'public'] as $prop) {
+    try {
+        $test->$prop = 42;
+    } catch (Error $e) {
+        echo $e::class, ": ", $e->getMessage(), "\n";
+    }
+}
+
+?>
+--EXPECT--
+int(1)
+int(2)
+int(3)
+int(4)
+Error: Cannot modify readonly property Test::$default
+Error: Cannot modify readonly property Test::$private
+Error: Cannot modify readonly property Test::$protected
+Error: Cannot modify readonly property Test::$public
diff --git a/Zend/tests/readonly_props/readonly_with_default_inheritance.phpt b/Zend/tests/readonly_props/readonly_with_default_inheritance.phpt
new file mode 100644
index 000000000000..8b285dcdd769
--- /dev/null
+++ b/Zend/tests/readonly_props/readonly_with_default_inheritance.phpt
@@ -0,0 +1,40 @@
+--TEST--
+Readonly property with default value and inheritance
+--FILE--
+<?php
+
+class ParentDefault {
+    public readonly int $prop = 1;
+}
+
+class ChildInherits extends ParentDefault {}
+
+class ChildOverrides extends ParentDefault {
+    public readonly int $prop = 2;
+}
+
+class PrivateParent {
+    private readonly int $prop = 3;
+
+    public function getParentProp(): int {
+        return $this->prop;
+    }
+}
+
+class PrivateChild extends PrivateParent {
+    public readonly int $prop = 4;
+}
+
+var_dump(new ChildInherits()->prop);
+var_dump(new ChildOverrides()->prop);
+
+$privateChild = new PrivateChild();
+var_dump($privateChild->getParentProp());
+var_dump($privateChild->prop);
+
+?>
+--EXPECT--
+int(1)
+int(2)
+int(3)
+int(4)
diff --git a/Zend/tests/readonly_props/readonly_with_default_interface.phpt b/Zend/tests/readonly_props/readonly_with_default_interface.phpt
new file mode 100644
index 000000000000..a20d869dc661
--- /dev/null
+++ b/Zend/tests/readonly_props/readonly_with_default_interface.phpt
@@ -0,0 +1,29 @@
+--TEST--
+Readonly property with default value satisfies get-only interface property
+--FILE--
+<?php
+
+interface I {
+    public int $prop { get; }
+}
+
+class C implements I {
+    public readonly int $prop = 42;
+}
+
+var_dump(new C()->prop);
+
+interface J {
+    public int $prop { get; set; }
+}
+
+// does not satisfy set
+class D implements J {
+    public readonly int $prop = 42;
+}
+
+?>
+--EXPECTF--
+int(42)
+
+Fatal error: Set access level of D::$prop must be omitted (as in class J) in %s on line %d
diff --git a/Zend/tests/readonly_props/readonly_with_default_reflection.phpt b/Zend/tests/readonly_props/readonly_with_default_reflection.phpt
new file mode 100644
index 000000000000..b10191b202be
--- /dev/null
+++ b/Zend/tests/readonly_props/readonly_with_default_reflection.phpt
@@ -0,0 +1,35 @@
+--TEST--
+Reflection for readonly property with default value
+--FILE--
+<?php
+
+class Foo {
+    public readonly int $prop = 1;
+    public readonly ?string $nullable = null;
+}
+
+$rp = new ReflectionProperty(Foo::class, 'prop');
+var_dump($rp->isReadOnly());
+var_dump($rp->hasDefaultValue());
+var_dump($rp->getDefaultValue());
+var_dump(new ReflectionClass(Foo::class)->getDefaultProperties());
+
+$test = new Foo();
+try {
+    $rp->setValue($test, 2);
+} catch (Error $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+bool(true)
+bool(true)
+int(1)
+array(2) {
+  ["prop"]=>
+  int(1)
+  ["nullable"]=>
+  NULL
+}
+Error: Cannot modify readonly property Foo::$prop
diff --git a/Zend/tests/readonly_props/readonly_with_default_trait_mismatch.phpt b/Zend/tests/readonly_props/readonly_with_default_trait_mismatch.phpt
new file mode 100644
index 000000000000..6668b1d860bb
--- /dev/null
+++ b/Zend/tests/readonly_props/readonly_with_default_trait_mismatch.phpt
@@ -0,0 +1,20 @@
+--TEST--
+Readonly trait property default value mismatch
+--FILE--
+<?php
+
+trait T1 {
+    public readonly int $prop = 1;
+}
+
+trait T2 {
+    public readonly int $prop = 2;
+}
+
+class C {
+    use T1, T2;
+}
+
+?>
+--EXPECTF--
+Fatal error: T1 and T2 define the same property ($prop) in the composition of C. However, the definition differs and is considered incompatible. Class was composed in %s on line %d
diff --git a/Zend/tests/readonly_props/serialization.phpt b/Zend/tests/readonly_props/serialization.phpt
index f9e1f364673f..f51fce199a63 100644
--- a/Zend/tests/readonly_props/serialization.phpt
+++ b/Zend/tests/readonly_props/serialization.phpt
@@ -17,6 +17,18 @@ var_dump(unserialize($s));
 var_dump(unserialize("O:4:\"Test\":1:{s:4:\"prop\";i:2;}"));
 var_dump(unserialize("O:4:\"Test\":2:{s:4:\"prop\";i:2;s:4:\"prop\";i:3;}"));
 
+class TestDefault {
+    public readonly int $prop = 1;
+}
+
+var_dump($s = serialize(new TestDefault));
+var_dump(unserialize($s));
+
+// Unserialization still bypasses normal readonly assignment semantics.
+var_dump(unserialize("O:11:\"TestDefault\":0:{}"));
+var_dump(unserialize("O:11:\"TestDefault\":1:{s:4:\"prop\";i:2;}"));
+var_dump(unserialize("O:11:\"TestDefault\":2:{s:4:\"prop\";i:2;s:4:\"prop\";i:3;}"));
+
 ?>
 --EXPECT--
 string(30) "O:4:"Test":1:{s:4:"prop";i:1;}"
@@ -32,3 +44,20 @@ object(Test)#1 (1) {
   ["prop"]=>
   int(3)
 }
+string(38) "O:11:"TestDefault":1:{s:4:"prop";i:1;}"
+object(TestDefault)#1 (1) {
+  ["prop"]=>
+  int(1)
+}
+object(TestDefault)#1 (1) {
+  ["prop"]=>
+  int(1)
+}
+object(TestDefault)#1 (1) {
+  ["prop"]=>
+  int(2)
+}
+object(TestDefault)#1 (1) {
+  ["prop"]=>
+  int(3)
+}
diff --git a/Zend/tests/readonly_props/unset.phpt b/Zend/tests/readonly_props/unset.phpt
index b8bd4218fa0c..f276ecaf2148 100644
--- a/Zend/tests/readonly_props/unset.phpt
+++ b/Zend/tests/readonly_props/unset.phpt
@@ -54,6 +54,33 @@ try {
     echo $e->getMessage(), "\n";
 }
 
+class Test4 {
+    public readonly int $prop = 1;
+
+    public function __construct() {
+        try {
+            unset($this->prop);
+        } catch (Error $e) {
+            echo $e::class, ": ", $e->getMessage(), "\n";
+        }
+    }
+
+    public function __get($name) {
+        echo __METHOD__, "\n"; // lazy pattern does not work
+        $this->prop = 2;
+        return $this->prop;
+    }
+}
+
+$test = new Test4;
+var_dump($test->prop); // Don't call __get.
+try {
+    unset($test->prop);
+} catch (Error $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+var_dump($test->prop); // Still don't call __get.
+
 ?>
 --EXPECT--
 Cannot unset readonly property Test::$prop
@@ -62,3 +89,7 @@ int(1)
 int(1)
 Cannot unset readonly property Test2::$prop
 Cannot unset protected(set) readonly property Test3::$prop from global scope
+Error: Cannot unset readonly property Test4::$prop
+int(1)
+Error: Cannot unset readonly property Test4::$prop
+int(1)
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index ee57e1dafb87..7b190680cfcc 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -9240,11 +9240,6 @@ static void zend_compile_prop_decl(zend_ast *ast, zend_ast *type_ast, uint32_t f
 				zend_error_noreturn(E_COMPILE_ERROR, "Readonly property %s::$%s must have type",
 					ZSTR_VAL(ce->name), ZSTR_VAL(name));
 			}
-			if (!Z_ISUNDEF(value_zv)) {
-				zend_error_noreturn(E_COMPILE_ERROR,
-					"Readonly property %s::$%s cannot have default value",
-					ZSTR_VAL(ce->name), ZSTR_VAL(name));
-			}
 			if (flags & ZEND_ACC_STATIC) {
 				zend_error_noreturn(E_COMPILE_ERROR,
 					"Static property %s::$%s cannot be readonly",