diff --git a/system/Test/ReflectionHelper.php b/system/Test/ReflectionHelper.php
index 8ada8e76da59..4c25e3decd89 100644
--- a/system/Test/ReflectionHelper.php
+++ b/system/Test/ReflectionHelper.php
@@ -74,7 +74,12 @@ private static function getAccessibleRefProperty($obj, $property)
     public static function setPrivateProperty($obj, $property, $value)
     {
         $refProperty = self::getAccessibleRefProperty($obj, $property);
-        $refProperty->setValue($obj, $value);
+
+        if (is_object($obj)) {
+            $refProperty->setValue($obj, $value);
+        } else {
+            $refProperty->setValue(null, $value);
+        }
     }
 
     /**
diff --git a/tests/system/CLI/CLITest.php b/tests/system/CLI/CLITest.php
index e7a9264c8791..f0f455f8aeb7 100644
--- a/tests/system/CLI/CLITest.php
+++ b/tests/system/CLI/CLITest.php
@@ -438,13 +438,13 @@ public function testWindow(): void
     {
         $height = new ReflectionProperty(CLI::class, 'height');
         $height->setAccessible(true);
-        $height->setValue(null);
+        $height->setValue(null, null);
 
         $this->assertIsInt(CLI::getHeight());
 
         $width = new ReflectionProperty(CLI::class, 'width');
         $width->setAccessible(true);
-        $width->setValue(null);
+        $width->setValue(null, null);
 
         $this->assertIsInt(CLI::getWidth());
     }