diff --git a/tests/phpunit/tests/rest-api/rest-request.php b/tests/phpunit/tests/rest-api/rest-request.php
index 6ec0491f0c..20616e05f6 100644
--- a/tests/phpunit/tests/rest-api/rest-request.php
+++ b/tests/phpunit/tests/rest-api/rest-request.php
@@ -1008,6 +1008,7 @@ class Tests_REST_Request extends WP_UnitTestCase {
 
 	/**
 	 * @ticket 51255
+	 * @requires PHPUnit >= 6
 	 */
 	public function test_route_level_validate_callback() {
 		$request = new WP_REST_Request();
@@ -1032,6 +1033,7 @@ class Tests_REST_Request extends WP_UnitTestCase {
 
 	/**
 	 * @ticket 51255
+	 * @requires PHPUnit >= 6
 	 */
 	public function test_route_level_validate_callback_no_parameter_callbacks() {
 		$request = new WP_REST_Request();
@@ -1051,6 +1053,7 @@ class Tests_REST_Request extends WP_UnitTestCase {
 
 	/**
 	 * @ticket 51255
+	 * @requires PHPUnit >= 6
 	 */
 	public function test_route_level_validate_callback_is_not_executed_if_parameter_validation_fails() {
 		$request = new WP_REST_Request();
diff --git a/tests/phpunit/tests/rest-api/rest-server.php b/tests/phpunit/tests/rest-api/rest-server.php
index 0dbc308bf9..e8038adcb7 100644
--- a/tests/phpunit/tests/rest-api/rest-server.php
+++ b/tests/phpunit/tests/rest-api/rest-server.php
@@ -1571,6 +1571,7 @@ class Tests_REST_Server extends WP_Test_REST_TestCase {
 
 	/**
 	 * @ticket 50244
+	 * @requires PHPUnit >= 6
 	 */
 	public function test_callbacks_are_not_executed_if_request_validation_fails() {
 		$callback = $this->createPartialMock( 'stdClass', array( '__invoke' ) );