diff --git a/Spawn/Launcher.php b/Spawn/Launcher.php
index 1e4827f..c441609 100644
--- a/Spawn/Launcher.php
+++ b/Spawn/Launcher.php
@@ -588,7 +588,7 @@ public function getSignaled(): ?int
     /**
      * @codeCoverageIgnore
      */
-    public static function uvLoop(?\UVLoop $loop)
+    public static function uvLoop(\UVLoop $loop)
     {
         self::$uv = $loop;
     }
diff --git a/Spawn/Spawn.php b/Spawn/Spawn.php
index 78105dc..2d94313 100644
--- a/Spawn/Spawn.php
+++ b/Spawn/Spawn.php
@@ -151,9 +151,12 @@ public static function create(
      *
      * @codeCoverageIgnore
      */
-    public static function setup(?\UVLoop $loop = null, bool $isYield = true, bool $bypass = true, bool $useUv = true): void
+    public static function setup($loop, bool $isYield = true, bool $bypass = true, bool $useUv = true): void
     {
-        Launcher::uvLoop($loop);
+        if ($loop instanceof \UVLoop) {
+            Launcher::uvLoop($loop);
+        }
+
         self::$bypass = $bypass;
         self::$isYield = $isYield;
         self::$useUv = $useUv;