diff --git a/devel/arcanist-lib/files/patch-src_future_FutureProxy.php b/devel/arcanist-lib/files/patch-src_future_FutureProxy.php
new file mode 100644
--- /dev/null
+++ b/devel/arcanist-lib/files/patch-src_future_FutureProxy.php
@@ -0,0 +1,11 @@
+--- src/future/FutureProxy.php.orig	2024-10-31 19:50:21 UTC
++++ src/future/FutureProxy.php
+@@ -8,7 +8,7 @@ abstract class FutureProxy extends Future {
+ 
+   private $proxied;
+ 
+-  public function __construct(Future $proxied = null) {
++  public function __construct(?Future $proxied = null) {
+     if ($proxied) {
+       $this->setProxiedFuture($proxied);
+     }