diff --git a/tests/phpunit/tests/user.php b/tests/phpunit/tests/user.php
index eb11a0b178..a3f21481f7 100644
--- a/tests/phpunit/tests/user.php
+++ b/tests/phpunit/tests/user.php
@@ -214,7 +214,9 @@ class Tests_User extends WP_UnitTestCase {
 	 */
 	function test_user_unset_lowercase_id( $user ) {
 		// Test 'id' (lowercase)
+		$id = $user->id;
 		unset( $user->id );
+		$this->assertSame( $id, $user->id );
 		return $user;
 	}