diff --git a/src/wp-includes/ms-default-constants.php b/src/wp-includes/ms-default-constants.php
index c8dd091c0a..0f7d0ff6d3 100644
--- a/src/wp-includes/ms-default-constants.php
+++ b/src/wp-includes/ms-default-constants.php
@@ -114,12 +114,10 @@ function ms_file_constants() {
  * we will have translations loaded and can trigger warnings easily.
  *
  * @since 3.0.0
- *
- * @global boolean $subdomain_error
- * @global boolean $subdomain_error_warn
  */
 function ms_subdomain_constants() {
-	global $subdomain_error, $subdomain_error_warn;
+	static $subdomain_error = null;
+	static $subdomain_error_warn = null;
 
 	if ( false === $subdomain_error ) {
 		return;
diff --git a/tests/phpunit/tests/ms.php b/tests/phpunit/tests/ms.php
index 647f5eea49..185133d1e6 100644
--- a/tests/phpunit/tests/ms.php
+++ b/tests/phpunit/tests/ms.php
@@ -25,17 +25,6 @@ class Tests_MS extends WP_UnitTestCase {
 		$wpdb->suppress_errors( $this->suppress );
 	}
 
-	/**
-	 * @ticket 28697
-	 */
-	function test_ms_subdomain_constants() {
-		global $subdomain_error;
-
-		$this->assertFalse( $subdomain_error );
-		ms_subdomain_constants();
-		$this->assertFalse( $subdomain_error );
-	}
-
 	function test_remove_user_from_blog() {
 		$user1 = $this->factory->user->create_and_get();
 		$user2 = $this->factory->user->create_and_get();