diff --git a/lib/Cake/TestSuite/CakeTestSuiteDispatcher.php b/lib/Cake/TestSuite/CakeTestSuiteDispatcher.php
index bb81a4518..4f997c078 100644
--- a/lib/Cake/TestSuite/CakeTestSuiteDispatcher.php
+++ b/lib/Cake/TestSuite/CakeTestSuiteDispatcher.php
@@ -170,7 +170,9 @@ class CakeTestSuiteDispatcher {
 			} elseif (is_file($vendor . DS . 'phpunit.phar')) {
 				$backup = $GLOBALS['_SERVER']['SCRIPT_NAME'];
 				$GLOBALS['_SERVER']['SCRIPT_NAME'] = '-';
+				ob_start();
 				$included = include_once $vendor . DS . 'phpunit.phar';
+				ob_end_clean();
 				$GLOBALS['_SERVER']['SCRIPT_NAME'] = $backup;
 				return $included;
 			}