diff --git a/core/src/avm2/class.rs b/core/src/avm2/class.rs
index a339b1c0d1333..21dc4b702c650 100644
--- a/core/src/avm2/class.rs
+++ b/core/src/avm2/class.rs
@@ -1162,15 +1162,23 @@ impl<'gc> Class<'gc> {
             &'static str,
             Option<NativeMethodImpl>,
             Option<NativeMethodImpl>,
+            Multiname<'gc>,
         )],
     ) {
-        for &(name, getter, setter) in items {
+        for (name, getter, setter, prop_type) in items {
             if let Some(getter) = getter {
                 self.define_instance_trait(
                     mc,
                     Trait::from_getter(
-                        QName::new(namespace, name),
-                        Method::from_builtin(getter, name, mc),
+                        QName::new(namespace, *name),
+                        Method::from_builtin_and_params(
+                            *getter,
+                            name,
+                            vec![],
+                            prop_type.clone(),
+                            false,
+                            mc,
+                        ),
                     ),
                 );
             }
@@ -1178,8 +1186,15 @@ impl<'gc> Class<'gc> {
                 self.define_instance_trait(
                     mc,
                     Trait::from_setter(
-                        QName::new(namespace, name),
-                        Method::from_builtin(setter, name, mc),
+                        QName::new(namespace, *name),
+                        Method::from_builtin_and_params(
+                            *setter,
+                            name,
+                            vec![ParamConfig::of_type("val", prop_type.clone())],
+                            QName::new(namespace, "void").into(),
+                            false,
+                            mc,
+                        ),
                     ),
                 );
             }
diff --git a/core/src/avm2/globals/array.rs b/core/src/avm2/globals/array.rs
index d7dfc76a91540..9e248960a6428 100644
--- a/core/src/avm2/globals/array.rs
+++ b/core/src/avm2/globals/array.rs
@@ -7,8 +7,8 @@ use crate::avm2::error::range_error;
 use crate::avm2::method::{Method, NativeMethodImpl};
 use crate::avm2::object::{array_allocator, ArrayObject, FunctionObject, Object, TObject};
 use crate::avm2::value::Value;
-use crate::avm2::Error;
 use crate::avm2::QName;
+use crate::avm2::{Error, Multiname};
 use crate::string::AvmString;
 use bitflags::bitflags;
 use std::cmp::{min, Ordering};
@@ -1259,15 +1259,16 @@ pub fn create_class<'gc>(activation: &mut Activation<'_, 'gc>) -> Class<'gc> {
         Method::from_builtin(class_call, "<Array call handler>", mc),
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
-        &str,
-        Option<NativeMethodImpl>,
-        Option<NativeMethodImpl>,
-    )] = &[("length", Some(length), Some(set_length))];
+    let public_instance_properties = &[(
+        "length",
+        Some(length as _),
+        Some(set_length as _),
+        Multiname::new(activation.avm2().public_namespace_base_version, "uint"),
+    )];
     class.define_builtin_instance_properties(
         mc,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
 
     class.define_builtin_instance_methods(
diff --git a/core/src/avm2/globals/class.rs b/core/src/avm2/globals/class.rs
index b9bfcac912c44..b6bbaa510f1eb 100644
--- a/core/src/avm2/globals/class.rs
+++ b/core/src/avm2/globals/class.rs
@@ -2,11 +2,11 @@
 
 use crate::avm2::activation::Activation;
 use crate::avm2::class::{Class, ClassAttributes};
-use crate::avm2::method::{Method, NativeMethodImpl};
+use crate::avm2::method::Method;
 use crate::avm2::object::{Object, TObject};
 use crate::avm2::value::Value;
-use crate::avm2::Error;
 use crate::avm2::QName;
+use crate::avm2::{Error, Multiname};
 
 /// Implements `Class`'s instance initializer.
 ///
@@ -54,15 +54,16 @@ pub fn create_i_class<'gc>(
         gc_context,
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
-        &str,
-        Option<NativeMethodImpl>,
-        Option<NativeMethodImpl>,
-    )] = &[("prototype", Some(prototype), None)];
+    let public_instance_properties = &[(
+        "prototype",
+        Some(prototype as _),
+        None,
+        Multiname::any(activation.context.gc_context),
+    )];
     class_i_class.define_builtin_instance_properties(
         gc_context,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
 
     class_i_class.mark_traits_loaded(activation.context.gc_context);
diff --git a/core/src/avm2/globals/date.rs b/core/src/avm2/globals/date.rs
index d32293a0dbee5..f843c49365b84 100644
--- a/core/src/avm2/globals/date.rs
+++ b/core/src/avm2/globals/date.rs
@@ -5,8 +5,8 @@ use crate::avm2::class::Class;
 use crate::avm2::method::{Method, NativeMethodImpl};
 use crate::avm2::object::{date_allocator, DateObject, FunctionObject, Object, TObject};
 use crate::avm2::value::Value;
-use crate::avm2::Error;
 use crate::avm2::QName;
+use crate::avm2::{Error, Multiname};
 use crate::locale::{get_current_date_time, get_timezone};
 use crate::string::{utils as string_utils, AvmString, WStr};
 use chrono::{DateTime, Datelike, Duration, FixedOffset, LocalResult, TimeZone, Timelike, Utc};
@@ -1338,38 +1338,108 @@ pub fn create_class<'gc>(activation: &mut Activation<'_, 'gc>) -> Class<'gc> {
         Method::from_builtin(call_handler, "<Date call handler>", mc),
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
+    let number_multiname =
+        Multiname::new(activation.avm2().public_namespace_base_version, "Number");
+
+    let public_instance_properties: &[(
         &str,
         Option<NativeMethodImpl>,
         Option<NativeMethodImpl>,
+        Multiname<'gc>,
     )] = &[
-        ("time", Some(time), Some(set_time)),
-        ("milliseconds", Some(milliseconds), Some(set_milliseconds)),
-        ("seconds", Some(seconds), Some(set_seconds)),
-        ("minutes", Some(minutes), Some(set_minutes)),
-        ("hours", Some(hours), Some(set_hours)),
-        ("date", Some(date), Some(set_date)),
-        ("month", Some(month), Some(set_month)),
-        ("fullYear", Some(full_year), Some(set_full_year)),
+        ("time", Some(time), Some(set_time), number_multiname.clone()),
+        (
+            "milliseconds",
+            Some(milliseconds),
+            Some(set_milliseconds),
+            number_multiname.clone(),
+        ),
+        (
+            "seconds",
+            Some(seconds),
+            Some(set_seconds),
+            number_multiname.clone(),
+        ),
+        (
+            "minutes",
+            Some(minutes),
+            Some(set_minutes),
+            number_multiname.clone(),
+        ),
+        (
+            "hours",
+            Some(hours),
+            Some(set_hours),
+            number_multiname.clone(),
+        ),
+        ("date", Some(date), Some(set_date), number_multiname.clone()),
+        (
+            "month",
+            Some(month),
+            Some(set_month),
+            number_multiname.clone(),
+        ),
+        (
+            "fullYear",
+            Some(full_year),
+            Some(set_full_year),
+            number_multiname.clone(),
+        ),
         (
             "millisecondsUTC",
             Some(milliseconds_utc),
             Some(set_milliseconds_utc),
+            number_multiname.clone(),
+        ),
+        ("day", Some(day), None, number_multiname.clone()),
+        (
+            "secondsUTC",
+            Some(seconds_utc),
+            Some(set_seconds_utc),
+            number_multiname.clone(),
+        ),
+        (
+            "minutesUTC",
+            Some(minutes_utc),
+            Some(set_minutes_utc),
+            number_multiname.clone(),
+        ),
+        (
+            "hoursUTC",
+            Some(hours_utc),
+            Some(set_hours_utc),
+            number_multiname.clone(),
+        ),
+        (
+            "dateUTC",
+            Some(date_utc),
+            Some(set_date_utc),
+            number_multiname.clone(),
+        ),
+        (
+            "monthUTC",
+            Some(month_utc),
+            Some(set_month_utc),
+            number_multiname.clone(),
+        ),
+        (
+            "fullYearUTC",
+            Some(full_year_utc),
+            Some(set_full_year_utc),
+            number_multiname.clone(),
+        ),
+        ("dayUTC", Some(day_utc), None, number_multiname.clone()),
+        (
+            "timezoneOffset",
+            Some(timezone_offset),
+            None,
+            number_multiname.clone(),
         ),
-        ("day", Some(day), None),
-        ("secondsUTC", Some(seconds_utc), Some(set_seconds_utc)),
-        ("minutesUTC", Some(minutes_utc), Some(set_minutes_utc)),
-        ("hoursUTC", Some(hours_utc), Some(set_hours_utc)),
-        ("dateUTC", Some(date_utc), Some(set_date_utc)),
-        ("monthUTC", Some(month_utc), Some(set_month_utc)),
-        ("fullYearUTC", Some(full_year_utc), Some(set_full_year_utc)),
-        ("dayUTC", Some(day_utc), None),
-        ("timezoneOffset", Some(timezone_offset), None),
     ];
     class.define_builtin_instance_properties(
         mc,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
     class.define_builtin_instance_methods(
         mc,
diff --git a/core/src/avm2/globals/function.rs b/core/src/avm2/globals/function.rs
index b75ce24f2462d..c6d03210632bd 100644
--- a/core/src/avm2/globals/function.rs
+++ b/core/src/avm2/globals/function.rs
@@ -7,8 +7,8 @@ use crate::avm2::globals::array::resolve_array_hole;
 use crate::avm2::method::{Method, NativeMethodImpl};
 use crate::avm2::object::{function_allocator, FunctionObject, Object, TObject};
 use crate::avm2::value::Value;
-use crate::avm2::Error;
 use crate::avm2::QName;
+use crate::avm2::{Error, Multiname};
 
 /// Implements `Function`'s instance initializer.
 pub fn instance_init<'gc>(
@@ -252,18 +252,24 @@ pub fn create_class<'gc>(
         AS3_INSTANCE_METHODS,
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
-        &str,
-        Option<NativeMethodImpl>,
-        Option<NativeMethodImpl>,
-    )] = &[
-        ("prototype", Some(prototype), Some(set_prototype)),
-        ("length", Some(length), None),
+    let public_instance_properties = &[
+        (
+            "prototype",
+            Some(prototype as _),
+            Some(set_prototype as _),
+            Multiname::any(activation.context.gc_context),
+        ),
+        (
+            "length",
+            Some(length as _),
+            None,
+            Multiname::new(activation.avm2().public_namespace_base_version, "int"),
+        ),
     ];
     function_i_class.define_builtin_instance_properties(
         gc_context,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
 
     const CONSTANTS_INT: &[(&str, i32)] = &[("length", 1)];
diff --git a/core/src/avm2/globals/namespace.rs b/core/src/avm2/globals/namespace.rs
index dff720bc0f160..59d185908ddaf 100644
--- a/core/src/avm2/globals/namespace.rs
+++ b/core/src/avm2/globals/namespace.rs
@@ -7,9 +7,9 @@ use crate::avm2::error::make_error_1098;
 use crate::avm2::method::{Method, NativeMethodImpl};
 use crate::avm2::object::{namespace_allocator, FunctionObject, Object, TObject};
 use crate::avm2::value::Value;
-use crate::avm2::Error;
 use crate::avm2::Namespace;
 use crate::avm2::QName;
+use crate::avm2::{Error, Multiname};
 use crate::string::AvmString;
 
 // All of these methods will be defined as both
@@ -194,15 +194,24 @@ pub fn create_class<'gc>(activation: &mut Activation<'_, 'gc>) -> Class<'gc> {
         Method::from_builtin(class_call, "<Namespace call handler>", mc),
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
-        &str,
-        Option<NativeMethodImpl>,
-        Option<NativeMethodImpl>,
-    )] = &[("prefix", Some(prefix), None), ("uri", Some(uri), None)];
+    let public_instance_properties = &[
+        (
+            "prefix",
+            Some(prefix as _),
+            None,
+            Multiname::any(activation.context.gc_context),
+        ),
+        (
+            "uri",
+            Some(uri as _),
+            None,
+            Multiname::new(activation.avm2().public_namespace_base_version, "String"),
+        ),
+    ];
     class.define_builtin_instance_properties(
         mc,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
 
     const CONSTANTS_INT: &[(&str, i32)] = &[("length", 2)];
diff --git a/core/src/avm2/globals/string.rs b/core/src/avm2/globals/string.rs
index e975ef23995e5..4c98ef49d3c32 100644
--- a/core/src/avm2/globals/string.rs
+++ b/core/src/avm2/globals/string.rs
@@ -7,9 +7,9 @@ use crate::avm2::method::{Method, NativeMethodImpl};
 use crate::avm2::object::{primitive_allocator, FunctionObject, Object, TObject};
 use crate::avm2::regexp::RegExpFlags;
 use crate::avm2::value::Value;
-use crate::avm2::Error;
 use crate::avm2::QName;
 use crate::avm2::{ArrayObject, ArrayStorage};
+use crate::avm2::{Error, Multiname};
 use crate::string::{AvmString, WString};
 
 // All of these methods will be defined as both
@@ -702,15 +702,16 @@ pub fn create_class<'gc>(activation: &mut Activation<'_, 'gc>) -> Class<'gc> {
         Method::from_builtin(call_handler, "<String call handler>", mc),
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
-        &str,
-        Option<NativeMethodImpl>,
-        Option<NativeMethodImpl>,
-    )] = &[("length", Some(length), None)];
+    let public_instance_properties = &[(
+        "length",
+        Some(length as _),
+        None,
+        Multiname::new(activation.avm2().public_namespace_base_version, "int"),
+    )];
     class.define_builtin_instance_properties(
         mc,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
     class.define_builtin_instance_methods(
         mc,
diff --git a/core/src/avm2/globals/vector.rs b/core/src/avm2/globals/vector.rs
index e6164b3a6c14c..f3dba296a2643 100644
--- a/core/src/avm2/globals/vector.rs
+++ b/core/src/avm2/globals/vector.rs
@@ -13,8 +13,8 @@ use crate::avm2::object::{
 };
 use crate::avm2::value::Value;
 use crate::avm2::vector::VectorStorage;
-use crate::avm2::Error;
 use crate::avm2::QName;
+use crate::avm2::{Error, Multiname};
 use crate::string::AvmString;
 use std::cmp::{max, min, Ordering};
 
@@ -964,18 +964,24 @@ pub fn create_builtin_class<'gc>(
         Method::from_builtin(class_call, "<Vector.<T> call handler>", mc),
     );
 
-    const PUBLIC_INSTANCE_PROPERTIES: &[(
-        &str,
-        Option<NativeMethodImpl>,
-        Option<NativeMethodImpl>,
-    )] = &[
-        ("length", Some(length), Some(set_length)),
-        ("fixed", Some(fixed), Some(set_fixed)),
+    let public_instance_properties = &[
+        (
+            "length",
+            Some(length as _),
+            Some(set_length as _),
+            Multiname::new(activation.avm2().public_namespace_base_version, "uint"),
+        ),
+        (
+            "fixed",
+            Some(fixed as _),
+            Some(set_fixed as _),
+            Multiname::new(activation.avm2().public_namespace_base_version, "Boolean"),
+        ),
     ];
     class.define_builtin_instance_properties(
         mc,
         activation.avm2().public_namespace_base_version,
-        PUBLIC_INSTANCE_PROPERTIES,
+        public_instance_properties,
     );
 
     const AS3_INSTANCE_METHODS: &[(&str, NativeMethodImpl)] = &[