diff --git a/cake/tests/lib/cake_test_case.php b/cake/tests/lib/cake_test_case.php
index c189e87af..5cb8a9647 100644
--- a/cake/tests/lib/cake_test_case.php
+++ b/cake/tests/lib/cake_test_case.php
@@ -242,7 +242,7 @@ class CakeTestCase extends UnitTestCase {
 		);
 		
 		if (is_string($params)) {
-			$params['return'] = $params;
+			$params = array('return' => $params);
 		}
 
 		$params = array_merge($default, $params);