diff --git a/lib/constructs/interface.js b/lib/constructs/interface.js
index ff2e6368..ec391b91 100644
--- a/lib/constructs/interface.js
+++ b/lib/constructs/interface.js
@@ -76,6 +76,105 @@ const IteratorPrototype = Object.create(utils.IteratorPrototype, {
   }
 });`;
   }
+}
+
+Interface.prototype.generateNamedPropertiesObject = function () {
+  if (!utils.isGlobal(this.idl)) {
+    return;
+  }
+
+  let overrideBuiltins = false;
+  let parent = this.idl;
+  while (parent) {
+    if (utils.getExtAttr(parent.extAttrs, 'OverrideBuiltins')) {
+      overrideBuiltins = true;
+    }
+
+    const members = parent.members.filter((m) =>
+      m.type === 'attribute' && utils.getExtAttr(m.extAttrs, 'Unforgeable')
+    );
+    const parentInterface = this.opts.interfaces[parent.inheritance];
+    parent = parentInterface && parentInterface.idl;
+  }
+
+  this.str += `
+function namedPropertiesIsVisible(P, O) {
+  if (!true) { // is supported
+    return false;
+  }
+
+  if (Object.getOwnPropertyDescriptor(O, P)) {
+    return false;
+  }
+  `;
+
+  if (overrideBuiltins) {
+    this.str += `
+  return true;`;
+  }
+
+  this.str += `
+  let prototype = Object.getPrototypeOf(O);
+  while (prototype) {
+    if (prototype.constructor.name.endsWith("PropertiesConstructor") && Object.getOwnPropertyDescriptor(prototype, P)) {
+      return false;
+    }
+    prototype = Object.getPrototypeOf(prototype);
+  }`;
+  this.str += `
+  return true;
+}`;
+
+  this.str += `var ${this.name}PropertiesConstructor = function () {
+  throw new TypeError("Illegal constructor");
+}\n`;
+
+  if (this.idl.inheritance) {
+    this.str += `${this.name}PropertiesConstructor.prototype = Object.create(${this.idl.inheritance}.interface.prototype);
+${this.name}PropertiesConstructor.prototype.constructor = ${this.name}PropertiesConstructor;\n`;
+  } else if (utils.getExtAttr(this.idl.extAttrs, 'LegacyArrayClass')) {
+    this.str += `${this.name}PropertiesConstructor.prototype = Object.create(Array.prototype);
+${this.name}PropertiesConstructor.prototype.constructor = ${this.name}PropertiesConstructor;\n`;
+  }
+
+  const getter = this.idl.members.filter((m) => m.getter)[0].name;
+  this.str += `
+const ${this.name}Properties = new Proxy(${this.name}PropertiesConstructor.prototype, {
+  defineProperty() {
+    return false;
+  },
+  deleteProperty() {
+    return false;
+  },
+  getOwnPropertyDescriptor(target, key) {
+    if (namedPropertiesIsVisible(key, target)) { // is visible
+      const value = target${getter ? "." + getter : "[utils.anonymousGetter]"}(key);
+      return {
+        value,
+        enumerable: true,
+        writable: true,
+        configurable: true
+      };
+    } else {
+      return Object.getOwnPropertyDescriptor(target, key);
+    }
+  },
+  get(target, key) {
+    if (namedPropertiesIsVisible(key, target)) { // is visible
+      const value = target${getter ? "." + getter : "[utils.anonymousGetter]"}(key);
+      return value;
+    } else {
+      return target[key];
+    }
+  },
+  has(target, key) {
+    if (namedPropertiesIsVisible(key, target)) { // is visible
+      return true;
+    } else {
+      return key in target;
+    }
+  }
+});\n\n`;
 };
 
 Interface.prototype.generateConstructor = function () {
@@ -116,9 +215,11 @@ Interface.prototype.generateConstructor = function () {
 }\n`;
   }
 
-  if (this.idl.inheritance) {
+  if (this.idl.inheritance && !utils.isGlobal(this.idl)) {
     this.str += `${this.name}.prototype = Object.create(${this.idl.inheritance}.interface.prototype);
 ${this.name}.prototype.constructor = ${this.name};\n`;
+  } else if (utils.isGlobal(this.idl)) {
+    this.str += `Object.setPrototypeOf(${this.name}.prototype, ${this.name}Properties);\n`;
   }
 };
 
@@ -406,6 +507,7 @@ module.exports = {
     defaultPrivateData = defaultPrivateData === undefined ? {} : defaultPrivateData;\n\n`;
   }
 
+  this.generateNamedPropertiesObject();
   this.generateConstructor();
   this.generateMixins();
 
diff --git a/lib/output/utils.js b/lib/output/utils.js
index 7bef1c35..d645697c 100644
--- a/lib/output/utils.js
+++ b/lib/output/utils.js
@@ -43,3 +43,6 @@ module.exports.tryWrapperForImpl = tryWrapperForImpl;
 module.exports.tryImplForWrapper = tryImplForWrapper;
 module.exports.iterInternalSymbol = iterInternalSymbol;
 module.exports.IteratorPrototype = IteratorPrototype;
+
+module.exports.anonymousGetter = Symbol("anonymousGetter");
+module.exports.anonymousSetter = Symbol("anonymousSetter");
diff --git a/lib/transformer.js b/lib/transformer.js
index cfba41d8..aff4ed6c 100644
--- a/lib/transformer.js
+++ b/lib/transformer.js
@@ -92,7 +92,8 @@ class Transformer {
             obj = new Interface(instruction, {
               implDir: path.resolve(outputDir, file.impl),
               implSuffix: this.options.implSuffix,
-              customTypes
+              customTypes,
+              interfaces
             });
             interfaces[obj.name] = obj;
             break;