diff --git a/tests/phpunit/tests/cache.php b/tests/phpunit/tests/cache.php
index d3805383a7..bc671ecd86 100644
--- a/tests/phpunit/tests/cache.php
+++ b/tests/phpunit/tests/cache.php
@@ -19,7 +19,9 @@ class Tests_Cache extends WP_UnitTestCase {
 	}
 
 	function &init_cache() {
-		$cache = new WP_Object_Cache();
+		global $wp_object_cache;
+		$cache_class = get_class( $wp_object_cache );
+		$cache = new $cache_class();
 		$cache->add_global_groups( array( 'global-cache-test', 'users', 'userlogins', 'usermeta', 'user_meta', 'site-transient', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss', 'global-posts', 'blog-id-cache' ) );
 		return $cache;
 	}