diff --git a/tests/phpunit/tests/rest-api/rest-schema-setup.php b/tests/phpunit/tests/rest-api/rest-schema-setup.php
index 1c643574795ad..1569e24e42f3b 100644
--- a/tests/phpunit/tests/rest-api/rest-schema-setup.php
+++ b/tests/phpunit/tests/rest-api/rest-schema-setup.php
@@ -769,6 +769,7 @@ private function normalize_fixture( $data, $path ) {
 				}
 
 				if ( 1 === preg_match( '/^post-\d+$/', $value ) ) {
+					// Normalize the class value to ensure test stability.
 					$data[ $key ] = 'post-1073';
 					continue;
 				}