@@ -307,32 +307,21 @@ MaybeLocal<Value> URLPattern::URLPatternInit::ToJsObject(
   auto tmpl = env->urlpatterninit_template();
   if (tmpl.IsEmpty()) {
     static constexpr std::string_view namesVec[] = {
-        "protocol",
-        "username",
-        "password",
+        "baseURL",
+        "hash",
         "hostname",
-        "port",
+        "password",
         "pathname",
+        "port",
+        "protocol",
         "search",
-        "hash",
-        "baseURL",
+        "username",
     };
     tmpl = DictionaryTemplate::New(isolate, namesVec);
     env->set_urlpatterninit_template(tmpl);
   }
 
-  MaybeLocal<Value> values[] = {
-      Undefined(isolate),  // protocol
-      Undefined(isolate),  // username
-      Undefined(isolate),  // password
-      Undefined(isolate),  // hostname
-      Undefined(isolate),  // port
-      Undefined(isolate),  // pathname
-      Undefined(isolate),  // search
-      Undefined(isolate),  // hash
-      Undefined(isolate),  // baseURL
-  };
-
+  MaybeLocal<Value> values[9];
   int idx = 0;
   Local<Value> temp;
   const auto trySet = [&](const std::optional<std::string>& val) {
@@ -346,28 +335,28 @@ MaybeLocal<Value> URLPattern::URLPatternInit::ToJsObject(
     return true;
   };
 
-  if (!trySet(init.protocol) || !trySet(init.username) ||
-      !trySet(init.password) || !trySet(init.hostname) || !trySet(init.port) ||
-      !trySet(init.pathname) || !trySet(init.search) || !trySet(init.hash) ||
-      !trySet(init.base_url)) {
+  if (!trySet(init.base_url) || !trySet(init.hash) || !trySet(init.hostname) ||
+      !trySet(init.password) || !trySet(init.pathname) || !trySet(init.port) ||
+      !trySet(init.protocol) || !trySet(init.search) ||
+      !trySet(init.username)) {
     return {};
   }
-  return NewDictionaryInstance(env->context(), tmpl, values);
+  return tmpl->NewInstance(context, values);
 }
 
 std::optional<ada::url_pattern_init> URLPattern::URLPatternInit::FromJsObject(
     Environment* env, Local<Object> obj) {
   ada::url_pattern_init init{};
   Local<String> components[] = {
-      env->protocol_string(),
-      env->username_string(),
-      env->password_string(),
+      env->base_url_string(),
+      env->hash_string(),
       env->hostname_string(),
-      env->port_string(),
+      env->password_string(),
       env->pathname_string(),
+      env->port_string(),
+      env->protocol_string(),
       env->search_string(),
-      env->hash_string(),
-      env->base_url_string(),
+      env->username_string(),
   };
   auto isolate = env->isolate();
   const auto set_parameter = [&](std::string_view key, std::string_view value) {
 
@@ -50,3 +50,43 @@ assert.throws(() => {
   assert.strictEqual(result.pathname.input, '/test');
   assert.strictEqual(result.pathname.groups.value, 'test');
 }
+
+{
+  const accessed = [];
+  const expected = [
+    'baseURL',
+    'hash',
+    'hostname',
+    'password',
+    'pathname',
+    'port',
+    'protocol',
+    'search',
+    'username',
+  ];
+  const init = new Proxy({}, {
+    get(target, name, receiver) {
+      accessed.push(name);
+      return Reflect.get(target, name, receiver);
+    },
+  });
+
+  new URLPattern(init);
+  assert.deepStrictEqual(accessed, expected);
+}
+
+{
+  const input = new URLPattern({ pathname: '/x' })
+    .exec({
+      protocol: 'https',
+      pathname: '/x',
+      username: undefined,
+    }).inputs[0];
+
+  assert.deepStrictEqual(Object.keys(input), ['pathname', 'protocol']);
+  assert.strictEqual('username' in input, false);
+  assert.deepStrictEqual({ ...input }, {
+    pathname: '/x',
+    protocol: 'https',
+  });
+}