diff --git a/phpunit/class-gutenberg-rest-template-controller-test.php b/phpunit/class-gutenberg-rest-template-controller-test.php
index 1460e6b4b9044..ab8a6a2530e94 100644
--- a/phpunit/class-gutenberg-rest-template-controller-test.php
+++ b/phpunit/class-gutenberg-rest-template-controller-test.php
@@ -191,6 +191,7 @@ public function test_get_item_works_with_a_single_slash( $endpoint_url ) {
 				'type'           => 'wp_template',
 				'wp_id'          => null,
 				'has_theme_file' => true,
+				'is_custom'      => false,
 			),
 			$data
 		);