diff --git a/tests/readme.txt b/tests/readme.txt
index b1e9b73..9a29954 100644
--- a/tests/readme.txt
+++ b/tests/readme.txt
@@ -21,7 +21,7 @@
 
 # Requirements
 
-1. PHP Unit
+1. PHP Unit >= 3.5.6
     - pear channel-discover pear.phpunit.de
     - pear install phpunit/PHPUnit