diff --git a/core/modules/simpletest/simpletest.install b/core/modules/simpletest/simpletest.install
index e5eb9a3..d81aae0 100644
--- a/core/modules/simpletest/simpletest.install
+++ b/core/modules/simpletest/simpletest.install
@@ -27,7 +27,7 @@ function simpletest_requirements($phase) {
   );
   if (!$has_curl) {
     $requirements['curl']['severity'] = REQUIREMENT_ERROR;
-    $requirements['curl']['description'] = t('The testing framework could not be installed because the PHP <a href="http://php.net/manual/curl.setup.php">cURL</a> library is not available.');
+    $requirements['curl']['description'] = t('The PHP <a href="@curl_url">cURL</a> library needs to be installed on the server. You should check the cURL status in PHP via phpinfo() or in the command line via `php -m | grep curl`. On Unix, you have to install the php5-curl extension. On Windows XAMPP, you have to enable the cURL extension by removing the ";" before "extension=php_curl.dll". Apache/nginx must be restarted after applying changes to the server.', array('@curl_url' => 'http://php.net/manual/curl.setup.php'));
   }
 
   // SimpleTest currently needs 2 cURL options which are incompatible with