diff --git a/src/RequestParametersCodegenBuilder.hack b/src/RequestParametersCodegenBuilder.hack
index 056b209..f04fc38 100644
--- a/src/RequestParametersCodegenBuilder.hack
+++ b/src/RequestParametersCodegenBuilder.hack
@@ -83,8 +83,7 @@ final class RequestParametersCodegenBuilder<T as RequestParametersBase>
             $parameter['optional'] ? 'Optional' : '',
             $getter_spec['accessorSuffix'],
           ),
-          $getter_spec['args']->map($arg ==> $arg->render($param_spec))
-            ->toVector(),
+          $getter_spec['args']->map($arg ==> $arg->render($param_spec)),
           /* semicolon at end = */ false,
         )
         ->add(',');
diff --git a/src/UriBuilderCodegenBuilder.hack b/src/UriBuilderCodegenBuilder.hack
index db00405..f0cc3dd 100644
--- a/src/UriBuilderCodegenBuilder.hack
+++ b/src/UriBuilderCodegenBuilder.hack
@@ -54,7 +54,7 @@ extends RequestParametersCodegenBuilderBase<UriBuilderCodegenBase<T>> {
               $param,
               \sprintf('$parameters[\'%s\']', $param->getName()),
             ),
-          )->toVector(),
+          ),
           /* semicolon at end = */ false,
         );
     }
diff --git a/tests/examples/GetRequestExampleController.hack b/tests/examples/GetRequestExampleController.hack
index 3664ade..2d4253f 100644
--- a/tests/examples/GetRequestExampleController.hack
+++ b/tests/examples/GetRequestExampleController.hack
@@ -37,9 +37,10 @@ implements
 
   final public static function __getParametersSpec(
   ): ImmVector<shape('spec' => RequestParameter, 'optional' => bool)> {
-    $params = static::getUriPattern()->getParameters()->map(
-      $param ==> shape('spec' => $param, 'optional' => false),
-    )->toVector();
+    $params = new Vector(
+      static::getUriPattern()->getParameters()
+        ->map($param ==> shape('spec' => $param, 'optional' => false)),
+    );
     $params[] = shape(
       'spec' => new StringRequestParameter(
         StringRequestParameterSlashes::WITHOUT_SLASHES,