diff --git a/src/Files/File.php b/src/Files/File.php
index 021949cb67..b0e67cec10 100644
--- a/src/Files/File.php
+++ b/src/Files/File.php
@@ -1759,6 +1759,7 @@ public function getMethodProperties($stackPtr)
      *    'scope'           => string,  // Public, private, or protected.
      *    'scope_specified' => boolean, // TRUE if the scope was explicitly specified.
      *    'is_static'       => boolean, // TRUE if the static keyword was found.
+     *    'is_readonly'     => boolean, // TRUE if the readonly keyword was found.
      *    'type'            => string,  // The type of the var (empty if no type specified).
      *    'type_token'      => integer, // The stack pointer to the start of the type
      *                                  // or FALSE if there is no type.
diff --git a/tests/Core/File/GetMemberPropertiesTest.inc b/tests/Core/File/GetMemberPropertiesTest.inc
index 3daf52c998..fe37230509 100644
--- a/tests/Core/File/GetMemberPropertiesTest.inc
+++ b/tests/Core/File/GetMemberPropertiesTest.inc
@@ -1,278 +1,282 @@
-<?php
-
-class TestMemberProperties
-{
-    /* testVar */
-    var $varA = true;
-
-    /* testVarType */
-    var ?int $varA = true;
-
-    /* testPublic */
-    public $varB = true;
-
-    /* testPublicType */
-    public string $varB = true;
-
-    /* testProtected */
-    protected $varC = true;
-
-    /* testProtectedType */
-    protected bool $varC = true;
-
-    /* testPrivate */
-    private $varD = true;
-
-    /* testPrivateType */
-    private array $varD = true;
-
-    /* testStatic */
-    static $varE = true;
-
-    /* testStaticType */
-    static ?string $varE = true;
-
-    /* testStaticVar */
-    static var $varF = true;
-
-    /* testVarStatic */
-    var static $varG = true;
-
-    /* testPublicStatic */
-    public static $varH = true;
-
-    /* testProtectedStatic */
-    static protected $varI = true;
-
-    /* testPrivateStatic */
-    private static $varJ = true;
-
-    /* testNoPrefix */
-    $varK = true;
-
-    /* testPublicStaticWithDocblock */
-    /**
-     * Comment here.
-     *
-     * @phpcs:ignore Standard.Category.Sniff -- because
-     * @var boolean
-     */
-    public static $varH = true;
-
-    /* testProtectedStaticWithDocblock */
-    /**
-     * Comment here.
-     *
-     * @phpcs:ignore Standard.Category.Sniff -- because
-     * @var boolean
-     */
-    static protected $varI = true;
-
-    /* testPrivateStaticWithDocblock */
-    /**
-     * Comment here.
-     *
-     * @phpcs:ignore Standard.Category.Sniff -- because
-     * @var boolean
-     */
-    private static $varJ = true;
-
-    public float
-    /* testGroupType 1 */
-    $x,
-    /* testGroupType 2 */
-    $y;
-
-    public static ?string
-    /* testGroupNullableType 1 */
-    $x = null,
-    /* testGroupNullableType 2 */
-    $y = null;
-
-    protected static
-        /* testGroupProtectedStatic 1 */
-        $varL,
-        /* testGroupProtectedStatic 2 */
-        $varM,
-        /* testGroupProtectedStatic 3 */
-        $varN;
-
-    private
-        /* testGroupPrivate 1 */
-        $varO = true,
-        /* testGroupPrivate 2 */
-        $varP = array( 'a' => 'a', 'b' => 'b' ),
-        /* testGroupPrivate 3 */
-        $varQ = 'string',
-        /* testGroupPrivate 4 */
-        $varR = 123,
-        /* testGroupPrivate 5 */
-        $varS = ONE / self::THREE,
-        /* testGroupPrivate 6 */
-        $varT = [
-            'a' => 'a',
-            'b' => 'b'
-        ],
-        /* testGroupPrivate 7 */
-        $varU = __DIR__ . "/base";
-
-
-    /* testMethodParam */
-    public function methodName($param) {
-        /* testImportedGlobal */
-        global $importedGlobal = true;
-
-        /* testLocalVariable */
-        $localVariable = true;
-    }
-
-    /* testPropertyAfterMethod */
-    private static $varV = true;
-
-    /* testMessyNullableType */
-    public /* comment
-         */ ? //comment
-        array $foo = [];
-
-    /* testNamespaceType */
-    public \MyNamespace\MyClass $foo;
-
-    /* testNullableNamespaceType 1 */
-    private ?ClassName $nullableClassType;
-
-    /* testNullableNamespaceType 2 */
-    protected ?Folder\ClassName $nullableClassType2;
-
-    /* testMultilineNamespaceType */
-    public \MyNamespace /** comment *\/ comment */
-           \MyClass /* comment */
-           \Foo $foo;
-
-}
-
-interface Base
-{
-    /* testInterfaceProperty */
-    protected $anonymous;
-}
-
-/* testGlobalVariable */
-$globalVariable = true;
-
-/* testNotAVariable */
-return;
-
-$a = ( $foo == $bar ? new stdClass() :
-    new class() {
-        /* testNestedProperty 1 */
-        public $var = true;
-
-        /* testNestedMethodParam 1 */
-        public function something($var = false) {}
-    }
-);
-
-function_call( 'param', new class {
-    /* testNestedProperty 2 */
-    public $year = 2017;
-
-    /* testNestedMethodParam 2 */
-    public function __construct( $open, $post_id ) {}
-}, 10, 2 );
-
-class PHP8Mixed {
-    /* testPHP8MixedTypeHint */
-    public static miXed $mixed;
-
-    /* testPHP8MixedTypeHintNullable */
-    // Intentional fatal error - nullability is not allowed with mixed, but that's not the concern of the method.
-    private ?mixed $nullableMixed;
-}
-
-class NSOperatorInType {
-    /* testNamespaceOperatorTypeHint */
-    public ?namespace\Name $prop;
-}
-
-$anon = class() {
-    /* testPHP8UnionTypesSimple */
-    public int|float $unionTypeSimple;
-
-    /* testPHP8UnionTypesTwoClasses */
-    private MyClassA|\Package\MyClassB $unionTypesTwoClasses;
-
-    /* testPHP8UnionTypesAllBaseTypes */
-    protected array|bool|int|float|NULL|object|string $unionTypesAllBaseTypes;
-
-    /* testPHP8UnionTypesAllPseudoTypes */
-    // Intentional fatal error - mixing types which cannot be combined, but that's not the concern of the method.
-    var false|mixed|self|parent|iterable|Resource $unionTypesAllPseudoTypes;
-
-    /* testPHP8UnionTypesIllegalTypes */
-    // Intentional fatal error - types which are not allowed for properties, but that's not the concern of the method.
-    public callable|static|void $unionTypesIllegalTypes;
-
-    /* testPHP8UnionTypesNullable */
-    // Intentional fatal error - nullability is not allowed with union types, but that's not the concern of the method.
-    public ?int|float $unionTypesNullable;
-
-    /* testPHP8PseudoTypeNull */
-    // Intentional fatal error - null pseudotype is only allowed in union types, but that's not the concern of the method.
-    public null $pseudoTypeNull;
-
-    /* testPHP8PseudoTypeFalse */
-    // Intentional fatal error - false pseudotype is only allowed in union types, but that's not the concern of the method.
-    public false $pseudoTypeFalse;
-
-    /* testPHP8PseudoTypeFalseAndBool */
-    // Intentional fatal error - false pseudotype is not allowed in combination with bool, but that's not the concern of the method.
-    public bool|FALSE $pseudoTypeFalseAndBool;
-
-    /* testPHP8ObjectAndClass */
-    // Intentional fatal error - object is not allowed in combination with class name, but that's not the concern of the method.
-    public object|ClassName $objectAndClass;
-
-    /* testPHP8PseudoTypeIterableAndArray */
-    // Intentional fatal error - iterable pseudotype is not allowed in combination with array or Traversable, but that's not the concern of the method.
-    public iterable|array|Traversable $pseudoTypeIterableAndArray;
-
-    /* testPHP8DuplicateTypeInUnionWhitespaceAndComment */
-    // Intentional fatal error - duplicate types are not allowed in union types, but that's not the concern of the method.
-    public int |string| /*comment*/ INT $duplicateTypeInUnion;
-
-    /* testPHP81NotReadonly */
-    private string $notReadonly;
-    /* testPHP81Readonly */
-    public readonly int $readonly;
-};
-
-$anon = class {
-    /* testPHP8PropertySingleAttribute */
-    #[PropertyWithAttribute]
-    public string $foo;
-
-    /* testPHP8PropertyMultipleAttributes */
-    #[PropertyWithAttribute(foo: 'bar'), MyAttribute]
-    protected ?int|float $bar;
-
-    /* testPHP8PropertyMultilineAttribute */
-    #[
-        PropertyWithAttribute(/* comment */ 'baz')
-    ]
-    private mixed $baz;
-};
-
-enum Suit
-{
-    /* testEnumProperty */
-    protected $anonymous;
-}
-
-enum Direction implements ArrayAccess
-{
-    case Up;
-    case Down;
-
-    /* testEnumMethodParamNotProperty */
-    public function offsetGet($val) { ... }
-}
+<?php
+
+class TestMemberProperties
+{
+    /* testVar */
+    var $varA = true;
+
+    /* testVarType */
+    var ?int $varA = true;
+
+    /* testPublic */
+    public $varB = true;
+
+    /* testPublicType */
+    public string $varB = true;
+
+    /* testProtected */
+    protected $varC = true;
+
+    /* testProtectedType */
+    protected bool $varC = true;
+
+    /* testPrivate */
+    private $varD = true;
+
+    /* testPrivateType */
+    private array $varD = true;
+
+    /* testStatic */
+    static $varE = true;
+
+    /* testStaticType */
+    static ?string $varE = true;
+
+    /* testStaticVar */
+    static var $varF = true;
+
+    /* testVarStatic */
+    var static $varG = true;
+
+    /* testPublicStatic */
+    public static $varH = true;
+
+    /* testProtectedStatic */
+    static protected $varI = true;
+
+    /* testPrivateStatic */
+    private static $varJ = true;
+
+    /* testNoPrefix */
+    $varK = true;
+
+    /* testPublicStaticWithDocblock */
+    /**
+     * Comment here.
+     *
+     * @phpcs:ignore Standard.Category.Sniff -- because
+     * @var boolean
+     */
+    public static $varH = true;
+
+    /* testProtectedStaticWithDocblock */
+    /**
+     * Comment here.
+     *
+     * @phpcs:ignore Standard.Category.Sniff -- because
+     * @var boolean
+     */
+    static protected $varI = true;
+
+    /* testPrivateStaticWithDocblock */
+    /**
+     * Comment here.
+     *
+     * @phpcs:ignore Standard.Category.Sniff -- because
+     * @var boolean
+     */
+    private static $varJ = true;
+
+    public float
+    /* testGroupType 1 */
+    $x,
+    /* testGroupType 2 */
+    $y;
+
+    public static ?string
+    /* testGroupNullableType 1 */
+    $x = null,
+    /* testGroupNullableType 2 */
+    $y = null;
+
+    protected static
+        /* testGroupProtectedStatic 1 */
+        $varL,
+        /* testGroupProtectedStatic 2 */
+        $varM,
+        /* testGroupProtectedStatic 3 */
+        $varN;
+
+    private
+        /* testGroupPrivate 1 */
+        $varO = true,
+        /* testGroupPrivate 2 */
+        $varP = array( 'a' => 'a', 'b' => 'b' ),
+        /* testGroupPrivate 3 */
+        $varQ = 'string',
+        /* testGroupPrivate 4 */
+        $varR = 123,
+        /* testGroupPrivate 5 */
+        $varS = ONE / self::THREE,
+        /* testGroupPrivate 6 */
+        $varT = [
+            'a' => 'a',
+            'b' => 'b'
+        ],
+        /* testGroupPrivate 7 */
+        $varU = __DIR__ . "/base";
+
+
+    /* testMethodParam */
+    public function methodName($param) {
+        /* testImportedGlobal */
+        global $importedGlobal = true;
+
+        /* testLocalVariable */
+        $localVariable = true;
+    }
+
+    /* testPropertyAfterMethod */
+    private static $varV = true;
+
+    /* testMessyNullableType */
+    public /* comment
+         */ ? //comment
+        array $foo = [];
+
+    /* testNamespaceType */
+    public \MyNamespace\MyClass $foo;
+
+    /* testNullableNamespaceType 1 */
+    private ?ClassName $nullableClassType;
+
+    /* testNullableNamespaceType 2 */
+    protected ?Folder\ClassName $nullableClassType2;
+
+    /* testMultilineNamespaceType */
+    public \MyNamespace /** comment *\/ comment */
+           \MyClass /* comment */
+           \Foo $foo;
+
+}
+
+interface Base
+{
+    /* testInterfaceProperty */
+    protected $anonymous;
+}
+
+/* testGlobalVariable */
+$globalVariable = true;
+
+/* testNotAVariable */
+return;
+
+$a = ( $foo == $bar ? new stdClass() :
+    new class() {
+        /* testNestedProperty 1 */
+        public $var = true;
+
+        /* testNestedMethodParam 1 */
+        public function something($var = false) {}
+    }
+);
+
+function_call( 'param', new class {
+    /* testNestedProperty 2 */
+    public $year = 2017;
+
+    /* testNestedMethodParam 2 */
+    public function __construct( $open, $post_id ) {}
+}, 10, 2 );
+
+class PHP8Mixed {
+    /* testPHP8MixedTypeHint */
+    public static miXed $mixed;
+
+    /* testPHP8MixedTypeHintNullable */
+    // Intentional fatal error - nullability is not allowed with mixed, but that's not the concern of the method.
+    private ?mixed $nullableMixed;
+}
+
+class NSOperatorInType {
+    /* testNamespaceOperatorTypeHint */
+    public ?namespace\Name $prop;
+}
+
+$anon = class() {
+    /* testPHP8UnionTypesSimple */
+    public int|float $unionTypeSimple;
+
+    /* testPHP8UnionTypesTwoClasses */
+    private MyClassA|\Package\MyClassB $unionTypesTwoClasses;
+
+    /* testPHP8UnionTypesAllBaseTypes */
+    protected array|bool|int|float|NULL|object|string $unionTypesAllBaseTypes;
+
+    /* testPHP8UnionTypesAllPseudoTypes */
+    // Intentional fatal error - mixing types which cannot be combined, but that's not the concern of the method.
+    var false|mixed|self|parent|iterable|Resource $unionTypesAllPseudoTypes;
+
+    /* testPHP8UnionTypesIllegalTypes */
+    // Intentional fatal error - types which are not allowed for properties, but that's not the concern of the method.
+    public callable|static|void $unionTypesIllegalTypes;
+
+    /* testPHP8UnionTypesNullable */
+    // Intentional fatal error - nullability is not allowed with union types, but that's not the concern of the method.
+    public ?int|float $unionTypesNullable;
+
+    /* testPHP8PseudoTypeNull */
+    // Intentional fatal error - null pseudotype is only allowed in union types, but that's not the concern of the method.
+    public null $pseudoTypeNull;
+
+    /* testPHP8PseudoTypeFalse */
+    // Intentional fatal error - false pseudotype is only allowed in union types, but that's not the concern of the method.
+    public false $pseudoTypeFalse;
+
+    /* testPHP8PseudoTypeFalseAndBool */
+    // Intentional fatal error - false pseudotype is not allowed in combination with bool, but that's not the concern of the method.
+    public bool|FALSE $pseudoTypeFalseAndBool;
+
+    /* testPHP8ObjectAndClass */
+    // Intentional fatal error - object is not allowed in combination with class name, but that's not the concern of the method.
+    public object|ClassName $objectAndClass;
+
+    /* testPHP8PseudoTypeIterableAndArray */
+    // Intentional fatal error - iterable pseudotype is not allowed in combination with array or Traversable, but that's not the concern of the method.
+    public iterable|array|Traversable $pseudoTypeIterableAndArray;
+
+    /* testPHP8DuplicateTypeInUnionWhitespaceAndComment */
+    // Intentional fatal error - duplicate types are not allowed in union types, but that's not the concern of the method.
+    public int |string| /*comment*/ INT $duplicateTypeInUnion;
+
+    /* testPHP81Readonly */
+    public readonly int $readonly;
+
+    /* testPHP81ReadonlyWithNullableType */
+    public readonly ?array $array;
+
+    /* testPHP81ReadonlyWithUnionType */
+    protected ReadOnly string|null $array;
+};
+
+$anon = class {
+    /* testPHP8PropertySingleAttribute */
+    #[PropertyWithAttribute]
+    public string $foo;
+
+    /* testPHP8PropertyMultipleAttributes */
+    #[PropertyWithAttribute(foo: 'bar'), MyAttribute]
+    protected ?int|float $bar;
+
+    /* testPHP8PropertyMultilineAttribute */
+    #[
+        PropertyWithAttribute(/* comment */ 'baz')
+    ]
+    private mixed $baz;
+};
+
+enum Suit
+{
+    /* testEnumProperty */
+    protected $anonymous;
+}
+
+enum Direction implements ArrayAccess
+{
+    case Up;
+    case Down;
+
+    /* testEnumMethodParamNotProperty */
+    public function offsetGet($val) { ... }
+}
diff --git a/tests/Core/File/GetMemberPropertiesTest.php b/tests/Core/File/GetMemberPropertiesTest.php
index d05814239d..cc709e69c7 100644
--- a/tests/Core/File/GetMemberPropertiesTest.php
+++ b/tests/Core/File/GetMemberPropertiesTest.php
@@ -51,6 +51,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -61,6 +62,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?int',
                     'nullable_type'   => true,
                 ],
@@ -71,6 +73,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -81,6 +84,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'string',
                     'nullable_type'   => false,
                 ],
@@ -91,6 +95,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -101,6 +106,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'bool',
                     'nullable_type'   => false,
                 ],
@@ -111,6 +117,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -121,6 +128,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'array',
                     'nullable_type'   => false,
                 ],
@@ -131,6 +139,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -141,6 +150,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '?string',
                     'nullable_type'   => true,
                 ],
@@ -151,6 +161,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -161,6 +172,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -171,6 +183,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -181,6 +194,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -191,6 +205,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -201,6 +216,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -211,6 +227,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -221,6 +238,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -231,6 +249,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'float',
                     'nullable_type'   => false,
                 ],
@@ -241,6 +260,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'float',
                     'nullable_type'   => false,
                 ],
@@ -251,6 +271,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '?string',
                     'nullable_type'   => true,
                 ],
@@ -261,6 +282,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '?string',
                     'nullable_type'   => true,
                 ],
@@ -271,6 +293,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -281,6 +304,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -291,6 +315,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -301,6 +326,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -311,6 +337,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -321,6 +348,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -331,6 +359,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -341,6 +370,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -351,6 +381,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -361,6 +392,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -371,6 +403,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -381,6 +414,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?array',
                     'nullable_type'   => true,
                 ],
@@ -391,6 +425,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '\MyNamespace\MyClass',
                     'nullable_type'   => false,
                 ],
@@ -401,6 +436,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?ClassName',
                     'nullable_type'   => true,
                 ],
@@ -411,6 +447,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?Folder\ClassName',
                     'nullable_type'   => true,
                 ],
@@ -421,6 +458,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '\MyNamespace\MyClass\Foo',
                     'nullable_type'   => false,
                 ],
@@ -431,6 +469,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -445,6 +484,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -455,6 +495,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '',
                     'nullable_type'   => false,
                 ],
@@ -465,6 +506,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => true,
+                    'is_readonly'     => false,
                     'type'            => 'miXed',
                     'nullable_type'   => false,
                 ],
@@ -475,6 +517,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?mixed',
                     'nullable_type'   => true,
                 ],
@@ -485,6 +528,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?namespace\Name',
                     'nullable_type'   => true,
                 ],
@@ -495,6 +539,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'int|float',
                     'nullable_type'   => false,
                 ],
@@ -505,6 +550,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'MyClassA|\Package\MyClassB',
                     'nullable_type'   => false,
                 ],
@@ -515,6 +561,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'array|bool|int|float|NULL|object|string',
                     'nullable_type'   => false,
                 ],
@@ -525,6 +572,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => false,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'false|mixed|self|parent|iterable|Resource',
                     'nullable_type'   => false,
                 ],
@@ -535,6 +583,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     // Missing static, but that's OK as not an allowed syntax.
                     'type'            => 'callable||void',
                     'nullable_type'   => false,
@@ -546,6 +595,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?int|float',
                     'nullable_type'   => true,
                 ],
@@ -556,6 +606,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'null',
                     'nullable_type'   => false,
                 ],
@@ -566,6 +617,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'false',
                     'nullable_type'   => false,
                 ],
@@ -576,6 +628,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'bool|FALSE',
                     'nullable_type'   => false,
                 ],
@@ -586,6 +639,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'object|ClassName',
                     'nullable_type'   => false,
                 ],
@@ -596,6 +650,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'iterable|array|Traversable',
                     'nullable_type'   => false,
                 ],
@@ -606,29 +661,41 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'int|string|INT',
                     'nullable_type'   => false,
                 ],
             ],
             [
-                '/* testPHP81NotReadonly */',
+                '/* testPHP81Readonly */',
                 [
-                    'scope'           => 'private',
+                    'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
-                    'is_readonly'     => false,
-                    'type'            => 'string',
+                    'is_readonly'     => true,
+                    'type'            => 'int',
                     'nullable_type'   => false,
                 ],
             ],
             [
-                '/* testPHP81Readonly */',
+                '/* testPHP81ReadonlyWithNullableType */',
                 [
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
                     'is_readonly'     => true,
-                    'type'            => 'int',
+                    'type'            => '?array',
+                    'nullable_type'   => true,
+                ],
+            ],
+            [
+                '/* testPHP81ReadonlyWithUnionType */',
+                [
+                    'scope'           => 'protected',
+                    'scope_specified' => true,
+                    'is_static'       => false,
+                    'is_readonly'     => true,
+                    'type'            => 'string|null',
                     'nullable_type'   => false,
                 ],
             ],
@@ -638,6 +705,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'public',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'string',
                     'nullable_type'   => false,
                 ],
@@ -648,6 +716,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'protected',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => '?int|float',
                     'nullable_type'   => true,
                 ],
@@ -658,6 +727,7 @@ public function dataGetMemberProperties()
                     'scope'           => 'private',
                     'scope_specified' => true,
                     'is_static'       => false,
+                    'is_readonly'     => false,
                     'type'            => 'mixed',
                     'nullable_type'   => false,
                 ],