diff --git a/composer.json b/composer.json
index 8f2edca6..1ccf55d7 100644
--- a/composer.json
+++ b/composer.json
@@ -33,7 +33,7 @@
     "type": "library",
     "require-dev": {
         "hhvm/hacktest": "^2.0",
-        "hhvm/type-assert": "^3.1",
+        "hhvm/type-assert": "^3.1|^4.0",
         "facebook/fbexpect": "^2.6.1",
         "hhvm/hhast": "^4.0",
         "facebook/difflib": "^1.0"
diff --git a/src/BaseCodeBuilder.hack b/src/BaseCodeBuilder.hack
index 4288b85c..f9c2bc63 100644
--- a/src/BaseCodeBuilder.hack
+++ b/src/BaseCodeBuilder.hack
@@ -124,7 +124,7 @@ abstract class BaseCodeBuilder {
    *
    * This is unsafe. Use `addf` instead if you have a literal format string.
    */
-  final protected function addvf(string $code, array<mixed> $args): this {
+  final protected function addvf(string $code, varray<mixed> $args): this {
     if ($code === null) {
       return $this;
     }
@@ -190,7 +190,7 @@ abstract class BaseCodeBuilder {
    * insert a newline. */
   final protected function addLineImplvf(
     ?string $code,
-    array<mixed> $args,
+    varray<mixed> $args,
   ): this {
     return $this->addvf((string)$code, $args)->newLine();
   }
diff --git a/src/key-value-render/HackBuilderValues.hack b/src/key-value-render/HackBuilderValues.hack
index 598890dc..be9ff01e 100644
--- a/src/key-value-render/HackBuilderValues.hack
+++ b/src/key-value-render/HackBuilderValues.hack
@@ -51,7 +51,7 @@ abstract final class HackBuilderValues {
   /** Render a `vec`-like PHP array literal */
   public static function valueArray<Tv>(
     IHackBuilderValueRenderer<Tv> $vr,
-  ): IHackBuilderValueRenderer<array<Tv>> {
+  ): IHackBuilderValueRenderer<varray<Tv>> {
     return new _Private\HackBuilderNativeValueCollectionRenderer(
       ContainerType::PHP_ARRAY,
       $vr,
@@ -62,7 +62,7 @@ abstract final class HackBuilderValues {
   public static function keyValueArray<Tk as arraykey, Tv>(
     IHackBuilderKeyRenderer<Tk> $kr,
     IHackBuilderValueRenderer<Tv> $vr,
-  ): IHackBuilderValueRenderer<array<Tk, Tv>> {
+  ): IHackBuilderValueRenderer<darray<Tk, Tv>> {
     return new _Private\HackBuilderNativeKeyValueCollectionRenderer(
       ContainerType::PHP_ARRAY,
       $kr,