diff --git a/tests/phpunit/tests/media.php b/tests/phpunit/tests/media.php
index 1ef1b93d4e91a..4b3fb26e84d3e 100644
--- a/tests/phpunit/tests/media.php
+++ b/tests/phpunit/tests/media.php
@@ -4436,7 +4436,7 @@ public function test_wp_get_loading_optimization_attributes_should_return_empty_
 		$result = null;
 		add_filter(
 			'the_content',
-			function( $content ) use ( &$result ) {
+			static function ( $content ) use ( &$result ) {
 				$attr   = $this->get_width_height_for_high_priority();
 				$result = wp_get_loading_optimization_attributes( 'img', $attr, 'something_completely_arbitrary' );
 				return $content;