diff --git a/src/core/Element.php b/src/core/Element.php
index 578fc196..0b78ad57 100644
--- a/src/core/Element.php
+++ b/src/core/Element.php
@@ -38,9 +38,8 @@ final public function toString(): string {
       $this->validateChildren();
     }
 
-    if ($this instanceof XHPAwaitable) {
-      // UNSAFE - interfaces don't support 'protected': facebook/hhvm#4830
-      $composed = await $this->asyncRender();
+    if ($this is XHPAwaitable) {
+      $composed = /* HH_FIXME[4112] protected */ await $this->asyncRender();
     } else {
       $composed = $this->render();
     }
diff --git a/src/core/XHPAwaitable.php b/src/core/XHPAwaitable.php
index 2a4d5e88..ab4376cd 100644
--- a/src/core/XHPAwaitable.php
+++ b/src/core/XHPAwaitable.php
@@ -17,5 +17,5 @@
  */
 interface XHPAwaitable {
   require extends :x:element;
-  // protected function asyncRender(): Awaitable<XHPRoot>
+  protected function asyncRender(): Awaitable<XHPRoot>;
 }
diff --git a/src/html/XHPBaseHTMLHelpers.php b/src/html/XHPBaseHTMLHelpers.php
index 9f3f4928..9e848aef 100644
--- a/src/html/XHPBaseHTMLHelpers.php
+++ b/src/html/XHPBaseHTMLHelpers.php
@@ -17,7 +17,7 @@ trait XHPBaseHTMLHelpers implements HasXHPBaseHTMLHelpers {
    */
   public function addClass(string $class): this {
     try {
-      $current_class = /* UNSAFE_EXPR */ $this->:class;
+      $current_class = ($this->getAttributes()['class'] ?? '') as string;
       return $this->setAttribute('class', trim($current_class.' '.$class));
     } catch (XHPInvalidAttributeException $error) {
       throw new XHPException(
@@ -42,7 +42,7 @@ public function conditionClass(bool $cond, string $class): this {
    * will only be generated if one has not already been set.
    */
   public function requireUniqueID(): string {
-    $id = /* UNSAFE_EXPR */ $this->:id;
+    $id = $this->getAttributes()['id'] ?? null;
     if ($id === null || $id === '') {
       try {
         $id = bin2hex(random_bytes(5));
diff --git a/tests/HackEnumAttributesTest.php b/tests/HackEnumAttributesTest.php
index a532d3b1..7893cb9a 100644
--- a/tests/HackEnumAttributesTest.php
+++ b/tests/HackEnumAttributesTest.php
@@ -41,9 +41,9 @@ public function testValidValues(): void {
 
   public function testValidRawValues(): void {
     // UNSAFE
-    $x = <test:hack-enum-attribute foo={1} />;
+    $x = <test:hack-enum-attribute foo={/* HH_IGNORE_ERROR[4110] */ 1} />;
     expect($x->toString())->toBeSame('<div>HERP</div>');
-    $x = <test:hack-enum-attribute foo={2} />;
+    $x = <test:hack-enum-attribute foo={/* HH_IGNORE_ERROR[4110] */2} />;
     expect($x->toString())->toBeSame('<div>DERP</div>');
   }