diff --git a/tests/phpunit/tests/admin/includesPlugin.php b/tests/phpunit/tests/admin/includesPlugin.php
index 6ba4cb33e0e1c..7542db6b59b36 100644
--- a/tests/phpunit/tests/admin/includesPlugin.php
+++ b/tests/phpunit/tests/admin/includesPlugin.php
@@ -366,7 +366,7 @@ public function test_get_plugin_files_single() {
 	public function test_get_plugin_files_folder() {
 		$plugin_dir = WP_PLUGIN_DIR . '/list_files_test_plugin';
 		@mkdir( $plugin_dir );
-		$plugin = $this->_create_plugin( null, 'list_files_test_plugin.php', $plugin_dir );
+		$plugin = $this->_create_plugin( '', 'list_files_test_plugin.php', $plugin_dir );
 
 		$sub_dir = trailingslashit( dirname( $plugin[1] ) ) . 'subdir';
 		mkdir( $sub_dir );