diff --git a/.hhconfig b/.hhconfig
index 4fa5a13..4886645 100644
--- a/.hhconfig
+++ b/.hhconfig
@@ -3,3 +3,4 @@ safe_array = true
 safe_vector_array = true
 unsafe_rx = false
 ignored_paths = [ "vendor/.+/tests/.+", "vendor/.+/bin/.+" ]
+const_default_func_args = true
diff --git a/src/Nuxed/Asset/Package.hack b/src/Nuxed/Asset/Package.hack
index 7cafe30..8aee460 100644
--- a/src/Nuxed/Asset/Package.hack
+++ b/src/Nuxed/Asset/Package.hack
@@ -6,10 +6,13 @@ use namespace HH\Lib\Str;
  * Basic package that adds a version to asset URLs.
  */
 class Package implements IPackage {
+private Context\IContext $context;
+
   public function __construct(
     private VersionStrategy\IVersionStrategy $versionStrategy,
-    private Context\IContext $context = new Context\NullContext(),
+    ?Context\IContext $context = null
   ) {
+    $this->context = $context ?? new Context\NullContext();
   }
 
   /**
diff --git a/src/Nuxed/Asset/PathPackage.hack b/src/Nuxed/Asset/PathPackage.hack
index 10bd075..e84b530 100644
--- a/src/Nuxed/Asset/PathPackage.hack
+++ b/src/Nuxed/Asset/PathPackage.hack
@@ -21,8 +21,9 @@ class PathPackage extends Package {
   public function __construct(
     string $basePath,
     IVersionStrategy $versionStrategy,
-    IContext $context = new Context\NullContext(),
+    ?IContext $context = null,
   ) {
+    $context ??= new Context\NullContext();
     parent::__construct($versionStrategy, $context);
 
     if ('' === $basePath) {
diff --git a/src/Nuxed/Asset/UrlPackage.hack b/src/Nuxed/Asset/UrlPackage.hack
index 193345f..70408da 100644
--- a/src/Nuxed/Asset/UrlPackage.hack
+++ b/src/Nuxed/Asset/UrlPackage.hack
@@ -26,8 +26,9 @@ class UrlPackage extends Package {
   public function __construct(
     Container<string> $baseUrls,
     VersionStrategy\IVersionStrategy $versionStrategy,
-    Context\IContext $context = new Context\NullContext(),
+    ?Context\IContext $context = null,
   ) {
+    $context ??= new Context\NullContext();
     parent::__construct($versionStrategy, $context);
 
     if (C\is_empty($baseUrls)) {