diff --git a/lib/phpunit/classes/advanced_testcase.php b/lib/phpunit/classes/advanced_testcase.php
index 8446e33..2b967d5 100644
--- a/lib/phpunit/classes/advanced_testcase.php
+++ b/lib/phpunit/classes/advanced_testcase.php
@@ -82,10 +82,13 @@ abstract class advanced_testcase extends PHPUnit_Framework_TestCase {
             $DB = phpunit_util::get_global_backup('DB');
 
             // Deal with any debugging messages.
+            ob_start();
             $debugerror = phpunit_util::display_debugging_messages();
+            $messages   = ob_get_contents();
+            ob_end_clean();
             $this->resetDebugging();
             if ($debugerror) {
-                trigger_error('Unenxpected debugging() call detected.', E_USER_NOTICE);
+                trigger_error('Unenxpected debugging() call detected.'."\n$messages", E_USER_NOTICE);
             }
 
         } catch (Exception $e) {