diff --git a/modules/simpletest/simpletest.install b/modules/simpletest/simpletest.install
index 01c892b33d8b2fdebd3d3fc51ff86a50011fb3ae..cd61969998da59705f48d7e385c882fe22655d70 100644
--- a/modules/simpletest/simpletest.install
+++ b/modules/simpletest/simpletest.install
@@ -37,7 +37,7 @@ function simpletest_requirements($phase) {
 
   $has_curl = function_exists('curl_init');
   $has_hash = function_exists('hash_hmac');
-  $has_domdocument = class_exists('DOMDocument');
+  $has_domdocument = method_exists('DOMDocument', 'loadHTML');
   $open_basedir = ini_get('open_basedir');
 
   $requirements['curl'] = array(